JP2010097923A - Power storage device and vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To early raise the temperature of a generating element stored within a power storage element. <P>SOLUTION: The power storage device includes a plurality of power storage elements 11 each having a positive electrode terminal 11a and a negative electrode terminal 11b; a plurality of bus bars 13 serially connecting the power storage elements 11; and a heating element 16 provided on at least one bus bar 13 of the plurality of bus bars 13. The positive electrode terminal 11a is higher in heat conductivity than the negative electrode terminal 11b, and the condition of S1>S2 is preferably satisfied, wherein S1 and S2 are respectively radial sectional areas of the positive electrode terminal 11a and the negative electrode terminal 11b. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a power storage device, and more particularly to a temperature rising structure of a power storage device.

  There have been proposed hybrid vehicles, electric vehicles, and the like that use a battery including a storage element such as a lithium ion battery as a power source. A hybrid vehicle is a vehicle that combines a motor and an internal combustion engine as a power mechanism, and the motor is driven by a current output from a battery.

  The internal resistance of the power storage element constituting the battery varies with temperature. FIG. 8 is an internal resistance-temperature characteristic diagram showing the relationship between the battery temperature and the internal resistance of a lithium ion battery (storage element). As shown in the figure, there is a correlation between the internal resistance and the battery temperature, and the internal resistance tends to increase as the battery temperature decreases. In particular, in the extremely low temperature (for example, −30 ° C.) region, the internal resistance value of the lithium ion battery becomes extremely high.

  When the internal resistance of the power storage element increases, the input / output current value is limited. For this reason, there is a possibility that a necessary battery output cannot be obtained. Moreover, there is a possibility that the energy generated when the vehicle is braked cannot be collected in the battery as regenerative energy. In this case, since the brake of the vehicle is switched to the mechanical brake, the energy at the time of braking is lost as heat energy, and the energy efficiency is lowered.

  Therefore, a temperature raising means for raising the temperature of the power generation element of the power storage element is required. Patent Document 1 discloses a vehicle battery device including a plurality of secondary batteries and a heating plate that warms the secondary batteries.

  The plurality of secondary batteries are arranged in parallel in close proximity to the surface of the heating plate. The heating plate includes an insulating substrate and a plurality of heaters fixed to the insulating substrate and connected to each other, and is fixed to the outer surface of the case that houses the plurality of secondary batteries. The battery device energizes the heater of the heating plate to heat the heater with Joule heat, and heats a plurality of secondary batteries with the heat generated by each heater.

Japanese Patent Laid-Open No. 2003-223938

  However, in the configuration of Patent Document 1, since the case is interposed between the heating plate and the cylindrical battery, the heat of the heating plate is difficult to transfer toward the inside of the cylindrical battery. . Therefore, the structure is not suitable for raising the temperature of the power generation element housed inside the cylindrical battery.

  In view of the above, an object of the present invention is to quickly raise the temperature of a power generation element housed inside a power storage element.

  In order to solve the above problems, a power storage device according to the present invention includes (1) a plurality of power storage elements each having a positive electrode terminal and a negative electrode terminal, a plurality of conductive plates that connect these power storage elements in series, And a heating element provided on at least one of the conductive plates.

  (2) In the configuration of (1), when the positive electrode terminal has higher thermal conductivity than the negative electrode terminal, and the cross-sectional areas in the radial direction of the positive electrode terminal and the negative electrode terminal are S1 and S2, respectively, S1 It is preferable to configure so as to satisfy the condition of> S2.

  According to the configuration of (2), it is possible to suppress variations in the temperature increase rate of each power storage element. Thereby, the lifetime reduction of an electrical storage apparatus can be suppressed.

  (3) In the configuration of (2), aluminum can be used as the positive electrode terminal. Moreover, copper can be used as the negative electrode terminal.

  (4) In the configurations of (1) to (3), the heating element can be provided only on one of the two conductive plates connected to the positive terminal and the negative terminal, respectively.

  According to the configuration of (4), it is possible to reduce the size and cost of the power storage device by reducing the heating elements without impairing the temperature rise effect of the power generation element.

  (5) In the configurations of (1) to (4), the plurality of power storage elements are stacked between a pair of end plates, and a first power storage element disposed adjacent to the end plates; A second power storage element disposed at a position farther from the end plate than the first power storage element, wherein the plurality of conductive plates are connected to the first power storage element. And a second conductive plate connected to the second power storage element, wherein the heating element provided on the first conductive plate is more than the heating element provided on the second conductive plate. Is also characterized by a large calorific value.

  In the configuration of (5), since the heat of the first power storage element is easily radiated through the end plate, the amount of heat generated by the heating element provided on the first conductive plate is provided on the second conductive plate. By making it larger than the heating element, it is possible to suppress variation in the temperature increase rate of each power storage element. Thereby, the lifetime reduction of an electrical storage apparatus can be suppressed.

(6) In the configurations of (1) to (5), based on the information acquired by the temperature information acquisition unit that acquires information about the temperature of the power storage element and the temperature information acquisition unit, the heating operation of the heating element is performed. And a controller that controls the heating element when the temperature of the power storage element is equal to or lower than a threshold value.

  According to the configuration of (6), it is possible to raise the temperature of the electric storage element in a scene where temperature increase control is required.

  (7) In the configuration of (6), the temperature information acquisition unit is provided in an element case that houses the power generation element of the power storage element, and the controller, when the temperature of the element case reaches a predetermined temperature, The heating operation by the heating element is stopped, and the predetermined temperature is lower than a target temperature of the power generation element by the heating operation of the heating element.

  According to the configuration of (7), it is possible to improve the heating efficiency and prevent waste of power used for the temperature raising time and the temperature raising.

  (8) In the configurations of (1) to (7), the heating element includes a resistor, a resistor housing case for housing the resistor, and a cement material filled in the resistor housing case. It is characterized by.

  According to the structure of (8), more heat radiated from the resistor can be contained in the cement material. Thereby, it is possible to effectively raise the temperature of the conductive plate.

  (9) In the configuration of (8), the resistor housing case can be brought into surface contact with the conductive plate.

  According to the configuration of (9), the heat of the heating element is easily transferred to the conductive plate, and the temperature of the conductive plate can be increased quickly.

  (10) In the configuration of (6) or (7), a plurality of heating groups each including a plurality of the heating elements connected in series via a conducting wire are connected in parallel, and the plurality of power storage elements are heated A plurality of power storage blocks are grouped according to speed, and each of the heat generation groups can be provided corresponding to each of the power storage blocks.

  According to the structure of (10), the fall of the temperature increase rate of an electrical storage element can be suppressed.

  (11) In the configuration of (10), a failure information acquisition unit for acquiring failure information of at least one of disconnection and short circuit of each of the heat generation groups can be provided.

  (12) In the configuration of (11), the failure information acquisition unit includes a plurality of the temperature information acquisition units provided in each of the power storage elements included in each of the power storage blocks, and the conductors in each of the heat generation groups. And a plurality of thermal fuses provided respectively in the circuit.

  According to the configuration of (12), it is possible to detect a failure of the heat generation group with a simple configuration.

  (13) In the configuration of (12), the power storage element provided with the temperature information acquisition unit may be a power storage element having the slowest temperature increase rate among the power storage blocks including the power storage element.

  According to the configuration of (13), the temperature sensor used for input / output control of the power storage device can be used also as the temperature information acquisition unit, so that cost reduction and size reduction can be achieved.

  (14) In the configuration of (12) or (13), the controller has no temperature rise based on information acquired by the plurality of temperature information acquisition units after instructing the heat generation operation to the plurality of heat generation groups. When this is detected, a signal instructing to stop the heat generation operation may be output.

  According to the configuration of (14), since the heat generation operation of all the heat generators can be stopped, the power consumption can be limited.

  (15) In the configuration of (11), the failure information acquisition unit is configured to include a plurality of voltage detection units for acquiring information related to voltage values between the heating elements included in each of the heat generation groups. You can also.

  According to the configuration of (15), the failure of the heat generation group can be detected with a simple configuration.

  (16) In the configuration of (15), when the controller detects a voltage change based on the information acquired in the plurality of voltage detection units after instructing the heat generation operation to the plurality of heat generation groups, A signal instructing to stop the heat generation operation may be output.

  According to the configuration of (16), since the heat generating operation of all the heat generators can be stopped, power consumption can be limited.

  According to the present invention, the temperature of the power generation element can be increased at an early stage.

It is a top view of an electrical storage apparatus. It is a perspective view of an electrical storage element. It is the block diagram which illustrated the temperature rising circuit of the electrical storage element. It is the flowchart which showed the temperature rising method of an electrical storage apparatus. 6 is a plan view of a power storage device of Example 2. FIG. It is a perspective view of an end plate. 6 is a flowchart illustrating a method for raising a temperature of a power storage device according to a third embodiment. It is the internal resistance-temperature characteristic figure which showed the relationship between the battery temperature of a lithium ion battery (electric storage element), and internal resistance. 6 is a plan view of a power storage device of Example 4. FIG. FIG. 6 is a block diagram of a power storage device according to a fourth embodiment. FIG. 12 is a block diagram of a power storage device according to a modification of Example 4.

  Examples of the present invention will be described below.

  A schematic configuration of a power storage device according to an embodiment of the present invention will be described with reference to FIG. Here, FIG. 1 is a plan view of the power storage device. The power storage device of the present embodiment can be arranged in a center console box provided between the driver's seat and the passenger seat, the lower side of the passenger seat, the trunk room (none of which are shown), and the like.

  The power storage device 1 includes an assembled battery 12 including a plurality of power storage elements 11. These power storage elements 11 are connected in series via a bus bar (conductive plate) 13. A refrigerant moving passage 14 is formed between the power storage elements 11 adjacent in the Y-axis direction. The refrigerant moving passage 14 extends in the Z-axis direction along the outer surface of the power storage element 11.

  An intake chamber (not shown) is attached to one end face of the assembled battery 12 in the Z-axis direction, and an exhaust chamber (not shown) is attached to the other end face. Cooling air is introduced into the refrigerant moving passage 14 from the intake chamber.

  The air that has flowed into the refrigerant movement passage 14 proceeds in the direction of the arrow along the outer surface of the power storage element 11, and cools the power generation element (see FIG. 2) 111 of the power storage element 11. Thereby, it can suppress that the electrical storage apparatus 1 deteriorates. Note that the air used for cooling the storage element 11 is exhausted from the exhaust chamber.

  The total positive terminal 11a and the total negative terminal 11b (terminals to which the bus bar 13 is not connected) of the power storage element 11 are electrically connected to an inverter (not shown) via wiring. This inverter is electrically connected to a motor (not shown), and this motor is driven using the output of power storage device 1. The driving force of the motor is transmitted to the wheels so that the vehicle can run.

  Each power storage element 11 is provided with a temperature sensor (temperature information acquisition unit) 15. As the temperature sensor 15, a thermistor element or a thermocouple can be used. Since the resistance value of the thermistor element changes according to the temperature change, the temperature of the power storage element 11 can be measured by detecting the change of the resistance value of the thermistor element.

  Some bus bars 13 are provided with heating elements 16. The heating element 16 is provided in the approximate center of the bus bar 13. When the heating element 16 generates heat, the bus bar 13 is heated. Since the bus bar 13 is electrically and mechanically connected to the positive electrode terminal 11a or the negative electrode terminal 11b of the power storage element 11, when the bus bar 13 is heated, the positive electrode terminal 11a or the negative electrode terminal 11b is heated.

  Since the positive electrode terminal 11a is connected to the power generation element 111 (details will be described later) of the power storage element 11, the power generation element 111 is heated when the positive electrode terminal 11a is heated. Thereby, the internal resistance of the power generation element 111 is lowered, and high current input / output is possible.

  Similarly, since the negative electrode terminal 11b is connected to the power generation element 111 of the power storage element 11, the power generation element 111 is heated when the negative electrode terminal 11b is heated. Thereby, the internal resistance of the power generation element 111 is lowered, and high current input / output is possible.

  With reference to FIG. 1 thru | or FIG. 3, the temperature rising structure of the electrical storage element 11 is demonstrated in detail. FIG. 2 is a perspective view of the electricity storage element 11, and shows a power generation element and a tab housed inside the electricity storage element 11 projected by dotted lines. FIG. 3 is a block diagram illustrating a circuit configuration for performing temperature increase control of the storage element 11.

  In these drawings, the electric storage element 11 has a square element case 112. The power generation element 111 is housed in the element case 112 in a wound state. The power generation element 111 includes a positive electrode body, a negative electrode body, and a separator disposed between the positive electrode body and the negative electrode body. The temperature sensor 15 is provided on the outer surface of the element case 112.

  Here, the positive electrode body is composed of a positive electrode current collector and a positive electrode layer applied to the surface of the positive electrode current collector. However, as will be described later, the positive electrode side end coating portion is composed of only the positive electrode current collector.

  The positive electrode layer is a layer containing an active material, a conductive agent, or the like corresponding to the positive electrode. Aluminum can be used for the positive electrode current collector. A lithium-transition metal composite oxide can be used for the active material of the positive electrode layer. As the conductive agent, acetylene black, carbon black, graphite, carbon fiber, or carbon nanotube can be used.

  Here, as shown in FIG. 2, the positive electrode body is formed only in a region other than the right end portion of the power generation element 111, that is, in the positive electrode body forming region. A positive electrode-side uncoated portion 111a is formed at the left end of the positive electrode body forming region. The positive electrode side end coating part 111a is an area | region part to which the positive electrode layer is not apply | coated among the electrical power collectors for positive electrodes.

  That is, in the positive electrode body formation region, a positive electrode current collector with a positive electrode layer applied on the surface is formed in the hatched region, and the positive electrode layer is formed in the non-hatched region (positive electrode side end coating portion 111a). Only the positive electrode current collector that is not coated on the surface is formed.

  A positive electrode side tab 113 is electrically and mechanically connected to the positive electrode side end coating portion 111a. As a connection method, welding can be used. Aluminum can be used for the positive electrode side tab 113. The positive electrode terminal 11a is electrically and mechanically connected to the end of the positive electrode tab 113 opposite to the end connected to the power generation element 111. According to the above-described configuration, the heat of the positive electrode terminal 11 a can be transferred to the power generation element 111 through the positive electrode side tab 113.

  The negative electrode body is composed of a negative electrode current collector and a negative electrode layer applied to the surface of the negative electrode current collector. However, as will be described later, the negative electrode side end coating portion is composed of only the negative electrode current collector.

  The negative electrode layer is a layer containing an active material, a conductive agent, or the like corresponding to the negative electrode. Copper can be used for the negative electrode current collector. Carbon can be used as the active material of the negative electrode layer. As the conductive agent, acetylene black, carbon black, graphite, carbon fiber, or carbon nanotube can be used.

  Here, as illustrated in FIG. 2, the negative electrode body is provided only in a region other than the left end portion of the power generation element 111, that is, in the negative electrode body forming region. A negative electrode side end coating portion 111b is formed at the right end of the negative electrode body forming region. The negative electrode side end coating part 111b is an area part of the negative electrode current collector 111b where the negative electrode layer is not applied.

  That is, in the negative electrode body formation region, a negative electrode current collector with a negative electrode layer applied on the surface is formed in the hatched region, and a negative electrode is formed in the non-hatched region (negative electrode side end coating portion 111b). Only the negative electrode current collector having no layer coated on the surface is formed.

  A negative electrode side tab 114 is electrically and mechanically connected to the negative electrode side end coating portion 111b. Nickel can be used for the negative electrode side tab 114. The negative electrode terminal 11b is electrically and mechanically connected to the end of the negative electrode tab 114 opposite to the end connected to the power generation element 111. According to the above configuration, the heat of the negative electrode terminal 11 b can be transferred to the power generation element 111 through the negative electrode side tab 114.

  Note that an electrode (a so-called bipolar electrode) in which a positive electrode layer is formed on one surface of the current collector and a negative electrode layer is formed on the other surface of the current collector can also be used. In this embodiment, an electrolytic solution is used, but a solid electrolyte formed of particles can also be used. Examples of the solid electrolyte include a polymer solid electrolyte and an inorganic solid electrolyte.

  Furthermore, in the present embodiment, the power storage element 11 has a square configuration, but the configuration is not limited to this, and a so-called cylindrical configuration may be used. That is, the power generation element 111 may be wound so that the element case 112 has a cylindrical shape and is accommodated in the element case 112.

Furthermore, although the storage element 11 is a lithium ion battery, the present invention is not limited to this, and a nickel-hydrogen battery can also be used. When the electricity storage element 11 is a nickel-hydrogen battery, nickel oxide is used as the active material for the positive electrode layer, and MmNi _(5-xyz) Al _x Mn _y Co _z is used as the active material for the negative electrode layer. A hydrogen storage alloy such as (Mm: Misch metal) can be used.

  Furthermore, in this embodiment, an air-cooled power storage device is used. However, the present invention is not limited to this, and the present invention can also be applied to a liquid-cooled power storage device. Here, the liquid cooling type power storage device is an assembled battery in which a plurality of power storage elements are connected in series via a bus bar, a cooling liquid for cooling the assembled battery, and a storage for storing the assembled battery and the cooling liquid. A power storage device including a container.

  As the heating element 16, a cement-type resistor can be used. As shown in FIG. 3, the heating element 16 includes a resistor housing case 16c and a resistor 16a housed in the resistor housing case 16c. The resistor housing case 16c is filled with a cement material 16b. The resistor 16a is sealed by the cement material 16b. In addition, all the structures of the heat generating body 16 of a present Example are the same.

  The resistor 16a is configured by bending a metal plate. For the metal plate, an alloy containing copper and nickel can be used. Ceramic can be used for the resistor housing case 16c. The ceramic may contain alumina in order to increase thermal conductivity. As the cement material 16b, a pasty insulating sealing material containing alumina powder or silica powder can be used.

  The heating elements 16 provided in each bus bar 13 are connected in series by a conducting wire 17. The conducting wire 17 is connected to a heater power supply 18. The resistor 16 a generates heat due to the current output from the heater power supply 18. A switching unit 19 is provided in the middle of the conducting wire 17. The switching unit 19 is connected to the controller 31. The controller 31 controls the switching operation of the switching unit 19.

  Thus, by sealing the periphery of the resistor 16a with the cement material 16b, more heat can be included in the cement material 16b. Thereby, the temperature of the bus bar 13 can be increased effectively.

  Further, as shown in FIG. 2, by bringing the heating element 16 into surface contact with the bus bar 13, heat transfer to the bus bar 13 is easier than in the heating method in which the resistor 16 a is in point contact with the bus bar 13. The temperature can be raised early.

  The bus bar 13 is connected to each of the positive electrode terminal 11a and the negative electrode terminal 11b of the power storage element 11 (excluding power storage elements having a total positive terminal and a total negative terminal), but the heating element 16 is connected to only one of the bus bars 13. Is provided. Since both the positive electrode terminal 11a and the negative electrode terminal 11b are connected to the power generation element 111 via the tabs 113 and 114, the power generation element 111 can be heated quickly by heating one of the bus bars 13. it can. Thereby, since the number of the heat generating bodies 16 is reduced, the power storage device can be downsized and the cost can be reduced.

  In the present embodiment, the heating element 16 is provided only in the power storage element 11 adjacent in the Z-axis direction, that is, the bus bar 13 that connects the adjacent storage elements 11 in the direction orthogonal to the stacking direction of the storage elements 11. The heating elements 16 can be arranged side by side in one direction (Y-axis direction). Thereby, the lead wires 17 connecting the heating elements 16 can be easily routed.

  Each temperature sensor 15 provided in each power storage element 11 is connected to a controller 31. Based on the temperature information output from these temperature sensors 15, the controller 31 turns on the switching unit 19 when the temperature of any one of the plurality of power storage elements 11 becomes lower than the lower limit temperature (threshold). Thus, the heating operation of the heating element 16 is started.

  Here, the lower limit temperature can be appropriately determined as a design value based on the correlation between the internal resistance of the power storage element 11 and the temperature. For example, in the characteristic diagram shown in FIG. 8, since the internal resistance increases when the battery temperature decreases to −30 ° C., −30 ° C. can be used as the lower limit temperature.

  In addition, based on the temperature information output from the temperature sensor 15, the controller 31 turns off the switching unit 19 and stops the heat generating operation of the heating element 16 when the temperatures of all the power storage elements 11 reach the target temperature.

  Here, the target temperature may be set to any value as long as an internal resistance value is obtained such that the input / output current value of the power storage element 11 becomes a desired value. However, it is preferable to set the target temperature to a lower temperature from the viewpoint of reducing the consumption of electric power used to generate heat from the heating element 16. In this embodiment, the target temperature is set to −10 ° C. Note that the storage element 11 that has reached the target temperature generates heat due to charge and discharge, and naturally rises in temperature toward a more suitable temperature (for example, 30 ° C.).

  Next, a method for raising the temperature of the power storage device will be described with reference to FIG. FIG. 4 is a flowchart illustrating a method for raising the temperature of the power storage device. The following flowchart is executed by the controller 31.

  In step S101, it is determined whether or not the ignition switch 32 is turned on. If the ignition switch 32 is turned on in step S101, the process proceeds to step S102.

  In step S102, temperature measurement is started. The controller 31 samples information on the temperature output from the temperature sensor 15 at a cycle of 1 second. In this flowchart, a thermistor is used as the temperature sensor 15. Therefore, “information about temperature” is a resistance value.

  In step S103, based on the information output from the temperature sensor 15, the temperature of the electrical storage element 11 is calculated, and it is determined whether the temperature of the electrical storage element 11 is -30 degreeC (lower limit temperature) or less. Here, when the temperature of any of the electricity storage elements 11 constituting the assembled battery 12 is −30 ° C. or lower, the process proceeds to step S104.

  In step S <b> 104, the switching unit 19 is turned on and the resistor 16 a of the heating element 116 is energized through the conducting wire 17. Thereby, the resistor 16a generates heat. The generated heat of the resistor 16a is transferred to the cement material 16b filled around the resistor 16a, and the heat of the cement material 16b is transferred to the resistor housing case 16c for housing the cement material 16b. The heat of the case 16 c is transferred to the bus bar 13.

  The heat of the bus bar 13 is transferred to the positive terminal 11 a or the negative terminal 11 b, and the heat of the positive terminal 11 a or the negative terminal 11 b is transferred to the power generation element 111. Thereby, the temperature of the power generation element 111 can be quickly increased.

In step S105, it is determined whether or not the temperature of the storage element 11 has risen to -10 ° C or higher. If the temperature has risen to −10 ° C. or more, the process proceeds to step S106. If the temperature has not risen to −10 ° C. or more, the process returns to step S104, and the energization operation to the heating element 16 is continued. In step S106, the energization operation of the heating element 16 to the resistor 16a is stopped, and this flow ends.
(Modification of Example 1)
In the present embodiment, since the resistors 16a having the same resistance value are connected in series, the heat generation amounts of all the heat generating members 16 are the same. This is because the heat generation amount is proportional to the product of the square of the current and the resistance value. It is necessary to raise the temperature of all the power storage elements 11 constituting the assembled battery 12 so that the temperature increase rate does not vary. This is because the deterioration rate of the power storage element 11 varies depending on the temperature, and the life of the power storage device 1 may be reduced.

  Therefore, when the cross-sectional area when the positive electrode terminal 11a is cut along the YZ plane is S1, and the cross-sectional area when the negative electrode terminal 11b is cut along the YZ plane is S2, the condition of S1> S2 is satisfied. Thus, it is preferable to set a dimensional ratio between the positive electrode terminal 11a and the negative electrode terminal 11b.

  Since the positive electrode terminal 11a is made of aluminum and has higher thermal conductivity than the negative electrode terminal 11b made of copper, the positive electrode terminal is set by setting the ratio of the cross-sectional area to cross-sectional area S1> cross-sectional area S2. It is possible to more effectively suppress variations in the heating rate of 11a and the negative electrode terminal 11b.

  The power storage device of this example has the same configuration as that of Example 1 except for the heating element. Therefore, only the heating element will be described. FIG. 5 is a plan view of the power storage device of this embodiment. The heating element of this embodiment includes a first heating element 161 and a second heating element 162. The first heating element 161 is provided on a bus bar (first conductive plate) 13 connected to a power storage element (first power storage element) 11 disposed adjacent to the end plate 25.

  The second heating element 162 is connected to the bus bar (second conductive plate) 13 connected to the power storage element (second power storage element) 11 disposed at a position farther from the end plate 25 than the first power storage element. Is provided. That is, in FIG. 5, the four power storage elements 11 in contact with the end plate 25 correspond to first power storage elements, and the remaining power storage elements 11 correspond to second power storage elements.

  The first and second heating elements 161 and 162 are both cement type resistors, and the second heating element 162 has the same configuration as the heating element 16 of the first embodiment.

  FIG. 6 is a perspective view of the end plate. As shown in the figure, leg portions 25b are formed at both ends of the end plate 25 in the Z-axis direction. The leg portion 25b projects in the Z-axis direction. A fastening hole 25c is formed in the leg 25b. A fastening bolt (not shown) inserted into the fastening hole 25c is fastened to a lower case (not shown). Thereby, the power storage device is fixed.

  A plurality of ribs 25 a extending in the Y-axis direction are formed on the XZ plane of the end plate 25. Therefore, the heat storage element 11, which is in contact with the end plate 25, that is, the heat of the first power storage element is structured to be easily dissipated through the rib 25a.

Therefore, in this embodiment, the amount of heat generated by the first heating element 161 is set larger than that of the second heating element 162. Specifically, the resistance value of the resistor of the first heating element 161 is set higher than that of the second heating element 162. Since the heat generation amount of the heat generating elements 161 and 162 is proportional to the product of the square of the current and the resistance value, the first heat generating element 161 has a larger heat generation amount than the second heat generating element 162. Thereby, the variation in the temperature increase rate of each electrical storage element 11 is suppressed, and the lifetime reduction of an electrical storage apparatus can be prevented.
(Modification of Example 2)
In this embodiment, the method of changing the resistance value of the resistor is used as a means for changing the amount of heat generated by the heat generator. However, the present invention is not limited to this, and other means can be used. For example, in the second heating element 162, the heat generation amount can be changed by making the thermal conductivity of the cement material higher than that of the first heating element 161 (the resistance value of the resistor is the same). Further, the power sources of the first heating element 161 and the second heating element 162 are separately provided, and the current value flowing through the first heating element 161 is set higher than the current value flowing through the second heating element 162. By doing so, the calorific value can be changed.

  Since the heating element 16 is connected to the power generation element 111 via the bus bar 13 and the tab 113 (or tab 114), when the heating element 16 starts a heat generation operation, the temperature of the power generation element 111 is higher than that of the element case 112. Will rise first. Therefore, the temperature detected by the temperature sensor 15 provided on the outer surface of the element case 112 is lower than the actual temperature of the power generation element 111.

  On the other hand, in the process of step S105 in the flowchart of FIG. 4, if the temperature of the power generation element 111 has reached the target temperature but the temperature of the element case 112 has not reached the target temperature, the heat generating operation of the heating element 16 is performed. Will continue. Therefore, the heating efficiency by the heating element 16 is lowered, and the temperature raising time is unnecessarily long. In order to solve this problem, in this embodiment, temperature increase control is performed by the following method.

  FIG. 7 is a flowchart showing a method of temperature rise control according to this embodiment. Since the processes from step S201 to step S204 are the same as the processes from step S101 to step S104 of the first embodiment, description thereof will be omitted.

  In step S205, the controller 31 calculates the temperature of the element case 112 of the power storage element 11 based on the temperature information output from the temperature sensor 15, and the calculated temperature is α (α is greater than the target temperature (−10 ° C.). It is determined whether or not the temperature is equal to or higher than a correction temperature (predetermined temperature) that is lower by (positive value) ° C. When the calculated temperature is equal to or higher than the correction temperature, the process proceeds to step S206 and the energization operation to the heating element 16 is stopped. When the calculated temperature is lower than the correction temperature, the process returns to step S204 and the energization to the heating element 16 is performed. Continue operation.

  α ° C. can be set in advance by obtaining a temperature difference between the power generation element 111 and the element case 112 through experiments or simulations.

  In this way, by using a correction temperature lower than the target temperature of the power generation element 111 as the stop temperature when stopping the heat generation operation of the heat generator 16, the heating efficiency is improved while the power generation element 111 is heated to the target temperature. In addition, it is possible to prevent wasteful heating time. In addition, other effects described in the first embodiment can be obtained.

The configuration of this embodiment can be applied to the configuration of Embodiment 2 as a matter of course.
(Modification of Example 3)
In the process of step S205, another corrected temperature obtained by adding α ° C. to the calculated temperature calculated based on the resistance value output from the temperature sensor 15 is calculated, and when the other corrected temperature is equal to or higher than the target temperature. The energization operation to the heating element 16 may be stopped.
(Modification)
In the first to third embodiments, the cement-type heating element 16 and the like are used. However, the present invention is not limited to this, and a PTC (Positive Temperature Coefficient) heater (heating element) can also be used. Here, when a current is passed through the PTC heater, self-heating occurs and the resistance increases.

  In the above embodiment, the temperature of all the power storage elements 11 constituting the assembled battery 12 is detected. However, the present invention is not limited to this, and only the temperature of the power storage elements 11 arranged adjacent to the end plate 25 is detected. It can also be configured to detect.

  As described in the second embodiment, since the temperature of the power storage element 11 in contact with the end plate 25 is likely to be lower than that of the other power storage elements 11, the temperature increase control is performed only by the temperature information of the power storage element 11 in contact with the end plate 25. This is because it can be done. In this case, part or all of the temperature sensor 15 provided in the other power storage element 11 can be omitted. Thereby, cost can be reduced.

  Moreover, the structure which provides the heat generating body 16 only in the one bus bar 13 may be sufficient. In this case, the power storage element 11 that is expected to have the lowest temperature can be examined in advance by simulation or the like, and the heating element 16 can be provided on the bus bar 13 connected to the power storage element 11. Thereby, cost can be reduced. Furthermore, the structure which provides the heat generating body 16 in all the bus bars 13 may be sufficient.

  With reference to FIG.9 and FIG.10, the electrical storage apparatus of Example 4 is demonstrated. FIG. 9 is a plan view of the power storage device of the fourth embodiment, and FIG. 10 is a block diagram of the power storage device of the fourth embodiment. Constituent elements having the same functions as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. The plurality of power storage elements 11 constituting the assembled battery 41 are grouped on the basis of the distance from the end plate 25. Here, referring to FIG. 9, the plurality of power storage elements 11 (power storage blocks) included in the first to fourth columns, counted from the end plate 25 positioned at the right end of the assembled battery 41, are grouped in groups A and 5 to 8. A plurality of power storage elements 11 (power storage blocks) included in group B, a plurality of power storage elements 11 (power storage blocks) included in columns 9 to 12 are group C, and a plurality of power storage elements 11 (power storage blocks) included in columns 13 to 16 are included. ) Is defined as group D, a plurality of power storage elements 11 (power storage blocks) included in columns 17 to 20 are defined as group E, and a plurality of power storage elements 11 (power storage blocks) included in columns 21 to 24 are defined as group F.

  In group A, a first heat generation group 51 including heating elements 511 to 514 is provided. Each of these heating elements 511 to 514 is provided on the bus bar 13 used for connecting the power storage elements 11 adjacent in the Z-axis direction, and is connected to each other in series. Therefore, the current value flowing through each of the heating elements 511 to 514 is the same. Group B is provided with a second heat generation group 52 including heating elements 521 to 524. Each of these heating elements 521 to 524 is provided on the bus bar 13 used for connecting the power storage elements 11 adjacent in the Z-axis direction, and is connected to each other in series. Therefore, the value of the current flowing through each of the heating elements 521 to 524 is the same. Group C is provided with a third heat generation group 53 including heat generating elements 531 to 534. Each of these heating elements 531 to 534 is provided on the bus bar 13 used for connecting the power storage elements 11 adjacent to each other in the Z-axis direction, and is connected to each other in series. Therefore, the current value flowing through each of the heating elements 531 to 534 is the same. Group D is provided with a fourth heat generation group 54 including heat generating elements 541 to 544. Each of the heating elements 541 to 544 is provided on the bus bar 13 used for connecting the power storage elements 11 adjacent in the Z-axis direction, and is connected to each other in series. Therefore, the current values flowing through the heating elements 541 to 544 are the same. The group E is provided with a fifth heat generation group 55 including heat generating elements 551 to 554. Each of these heating elements 551 to 554 is provided on the bus bar 13 used for connecting the power storage elements 11 adjacent to each other in the Z-axis direction, and is connected to each other in series. Therefore, the current values flowing through the heating elements 551 to 554 are the same. The group F is provided with a sixth heat generation group 56 including heat generating elements 561 to 564. Each of these heating elements 561 to 564 is provided on the bus bar 13 used for connecting the power storage elements 11 adjacent in the Z-axis direction, and is connected to each other in series. Therefore, the current value flowing through each of the heating elements 561 to 564 is the same.

  The first to sixth heat generation groups 51 to 56 are connected in parallel to each other, and the controller 31 controls the current flowing through the first to sixth heat generation groups 51 to 56. The controller 31 is connected to the DCDC converter 44. The DCDC converter 44 adjusts the electric power generated by the assembled battery 41 and outputs it to the controller 31. A PTC (Positive Temperature Coefficient) heater can also be used for each of the heating elements 511 to 564. Here, when a current is passed through the PTC heater, self-heating occurs and the resistance increases.

  The reason why the plurality of power storage elements 11 constituting the assembled battery 41 are grouped into grapes A to F will be described. This grouping corresponds to the temperature increase condition of the electric storage element 11 such that the closer to the end plate 25, the easier it is to touch the outside air and the heat is easily radiated. A comparative example 1 will be shown and described more specifically. In Comparative Example 1, all of the heating elements are composed of PTC heaters, and these heating elements are connected in series as in Example 1. When these heating elements are energized, the temperature rise rate of the power storage element 11 increases as the distance from the end plate 25 increases, so that the heating element located at the center has a higher resistance value. As a result, the value of the current flowing through each heating element is reduced, and the amount of heat generated by the heating element located in the region close to the end plate 25 is reduced, so that the overall rate of temperature increase is reduced.

  On the other hand, in the present embodiment, the heating elements 511 to 564 are grouped according to the temperature increase condition of the power storage element 11, so that the temperature increase time can be shorter than that of the configuration of Comparative Example 1. That is, even if the resistance value of the heating element (for example, the heating element 534) of the power storage element 11 that rises in temperature early increases, the heating element (for example, the heating element) of the power storage element 11 that has a slow temperature increase rate is linked to this. Since the value of the current flowing through 511) does not decrease, the temperature raising time can be shortened compared with the configuration of Comparative Example 1.

  The groups A to F are provided with first to sixth temperature sensors (temperature information acquisition units) 516 to 566, respectively. The first to sixth temperature sensors 516 to 566 are the power storage elements 11 located in the region closest to the end plate 25 among the power storage elements 11 included in each of the groups A to F (that is, the power storage devices having the slowest temperature increase rate). It is provided in the element 11). The controller 31 controls the heat generation operation of the first to sixth heat generation groups 51 to 56 based on signals output from the first to sixth temperature sensors 516 to 566 as in the first embodiment.

  These first to sixth temperature sensors 516 to 566 can also be used as temperature sensors for estimating the state of the assembled battery 41. That is, the input / output of the voltage of the assembled battery 41 is controlled based on the temperature information output from the first to sixth temperature sensors 516 to 566. Thereby, the number of temperature sensors can be reduced and cost reduction can be achieved. In addition, the controller 31 may perform control of voltage input / output of the assembled battery 41, or may be performed by another controller different from this.

  Here, the heating elements 511 to 564 may be short-circuited or disconnected due to secular change or the like. For example, when the heating element 511 is disconnected, the temperature of the power storage elements 11 included in the group A cannot be increased. Therefore, the assembled battery 41 may be overcharged. Therefore, in the present embodiment, a failure information acquisition unit is provided, and when the heating elements 511 to 564 are short-circuited or disconnected, the heating operation of all the heating elements 511 to 564 is stopped.

  Referring to FIG. 10, the failure information acquisition unit includes first to sixth temperature fuses 515 to 565 and first to sixth temperature sensors 516 to 516 provided in the first to sixth heat generation groups 51 to 56, respectively. 566 is included. These first to sixth thermal fuses 515 to 565 block the current flowing through the first to sixth heat generation groups 51 to 56 by forcibly blowing the fusible alloy by energization heating.

  In the above-described configuration, for example, when the heating element 511 is disconnected, no current flows through the first heating group 51 including the heating element 511, and the temperature raising operation of the power storage elements 11 included in the group A is stopped. Based on the temperature information output from the first temperature sensor 516, the controller 31 determines whether or not the temperature raising operation of the power storage elements 11 included in the group A has stopped, that is, whether or not the first heat generation group 51 has been disconnected. Can be determined. Further, when the first heat generation group 51 is disconnected, the controller 31 stops the energization operation of all the heat generating elements 511 to 564. Thereby, power consumption can also be reduced.

  In the above configuration, for example, when the heating element 511 is short-circuited, the value of the current flowing through the first heating group 51 is increased, and the first thermal fuse 515 included in the first heating group 51 is melted. Disconnect. Therefore, similarly to the above, based on the temperature information output from the first temperature sensor 516, it can be determined that the temperature raising operation of the power storage elements 11 included in the group A has stopped.

Here, a configuration in which all of the heating elements 511 to 564 are connected in parallel and a thermal fuse is provided in each of the heating elements 511 to 564 is also conceivable. However, with this configuration, the number of thermal fuses increases, resulting in high costs and contrary to the demand for miniaturization. On the other hand, in the present embodiment, since a plurality of power storage elements 11 are grouped according to the temperature rising rate and one temperature fuse is provided for each group, cost reduction and size reduction can be achieved. it can.
(Modification of Example 4)
Next, a modification of the failure information acquisition unit will be described with reference to FIG. FIG. 11 is a block diagram of a power storage device according to a modification. In the fourth embodiment, the presence / absence of a failure is determined based on the temperature information output from the temperature sensor, but in the present modification, the presence / absence of a failure is determined based on a voltage change in each of the first to sixth heat generation groups 51 to 56. . This will be specifically described below.

  In the first heat generation group 51, a voltage detection unit 517 is provided between the adjacent heat generation elements 511 and 512 to detect the voltage. In the above configuration, when the first heat generation group 51 is not disconnected or short-circuited, the voltage value V1 detected by the voltage detection unit 517 is V1≈1 / 4 * V0.

  On the other hand, when the heating element 511 is disconnected, it changes to V1≈V0, when the heating element 511 is short-circuited, it changes to V1≈0, and when any of the heating elements 512 to 514 is disconnected, V1≈ When it changes to 0 and one of the heating elements 512 to 514 is short-circuited, it changes to V1≈1 / 3 * V0. As described above, when the voltage value detected by the voltage detection unit 517 changes, the energization to all the heating elements 511 to 564 is immediately stopped as in the fourth embodiment. In the above-described configuration, the position of the voltage detection unit 517 can be changed between the heating element 513 and the heating element 514.

  In the second heat generation group 52, a voltage detection unit 527 is provided between the adjacent heat generation elements 521 and 522 to detect the voltage. In the third heat generation group 53, a voltage detection unit 537 is provided between the adjacent heat generation elements 531 and 532 and detects the voltage. In the fourth heat generation group 54, a voltage detection unit 547 is provided between the adjacent heat generation elements 541 and 542 to detect the voltage. In the fifth heat generation group 55, a voltage detection unit 557 is provided between the adjacent heat generation elements 551 and 552 to detect the voltage. In the sixth heat generation group 56, a voltage detection unit 567 is provided between the adjacent heat generation elements 561 and heat generation elements 562 to detect the voltage. Since the failure determination method for these second to sixth heat generation groups 52 to 56 is the same as that for the first heat generation group 51, description thereof is omitted.

  In the fourth embodiment (including the modification of the fourth embodiment), the power storage elements 11 are grouped according to the distance from the end plate 25, but the present invention is not limited to this. For example, when there is a heat source or a cooling source in the vicinity of the power storage element 11, the temperature rise distribution of the power storage element 11 also varies accordingly, and therefore it is preferable to perform grouping according to the temperature rise conditions of each assembled battery. .

  In the fourth embodiment, when a failure is detected, the heating operation of all the heating elements 511 to 564 is stopped. However, the present invention is not limited to this, and for example, a notification that notifies that a failure has been detected. Means can also be used. Here, as the notification means, for example, a notification means by voice output or a notification means by lamp lighting can be used.

DESCRIPTION OF SYMBOLS 1 Power storage device 11 Power storage element 11a Positive electrode terminal 11b Negative electrode terminal 12 41 Battery pack 13 Bus bar 14 Refrigerant movement path
15 516-566 Temperature sensor 16 511-564 Heating element 16a Resistor 16b Cement material 16c Resistor housing case 17 Conductor 18 Power supply for heater
DESCRIPTION OF SYMBOLS 19 Switching part 25 End plate 31 Controller 32 IG switch 51-56 Heat generation group 111 Power generation element 111a Positive electrode side end coating part 111b Negative electrode side end application part 112 Element case 113 Positive electrode side tab 114 Negative electrode side tab 161 First heating element 162 Second heating element
515-565 Thermal fuse 517-567 Voltage detector

Claims (17)

A plurality of power storage elements each having a positive terminal and a negative terminal;
A plurality of conductive plates connecting these power storage elements in series;
A heating element provided on at least one of the plurality of conductive plates;
A power storage device comprising: The positive electrode terminal has higher thermal conductivity than the negative electrode terminal, and when the cross-sectional areas in the radial direction of the positive electrode terminal and the negative electrode terminal are S1 and S2, respectively,
S1> S2
The power storage device according to claim 1, wherein the following condition is satisfied.   The power storage device according to claim 2, wherein the positive terminal is made of aluminum, and the negative terminal is made of copper.   The electrical storage device according to any one of claims 1 to 3, wherein the heating element is provided only on one of the two conductive plates connected to the positive terminal and the negative terminal, respectively. apparatus. The plurality of power storage elements are stacked between a pair of end plates, a first power storage element disposed adjacent to the end plate, and more distant from the end plate than the first power storage element A second power storage element disposed at a position,
The plurality of conductive plates include a first conductive plate connected to the first power storage element, and a second conductive plate connected to the second power storage element,
5. The heating element provided on the first conductive plate has a larger amount of heat generation than the heating element provided on the second conductive plate. 6. The power storage device described in 1. A temperature information acquisition unit for acquiring information on the temperature of the power storage element;
And a controller that controls the heat generation operation of the heat generating element based on the information acquired by the temperature information acquisition unit. The controller generates heat when the temperature of the power storage element is equal to or lower than a threshold value. The power storage device according to claim 1, wherein the power storage device is a power storage device. The temperature information acquisition unit is provided in an element case that houses a power generation element of the power storage element,
The controller stops the heat generation operation by the heating element when the temperature of the element case reaches a predetermined temperature, and the predetermined temperature is lower than a target temperature of the power generation element by the heat generation operation of the heating element. The power storage device according to claim 6.   The heating element includes a resistor, a resistor housing case for housing the resistor, and a cement material filled in the resistor housing case. The power storage device according to one.   The power storage device according to claim 8, wherein the resistor housing case is in surface contact with the conductive plate.   A plurality of heat generating groups each including a plurality of heat generating elements connected in series via a lead wire are connected in parallel, and the plurality of power storage elements are grouped into a plurality of power storage blocks according to a temperature rising rate. The power storage device according to claim 6, wherein each of the heat generation groups is provided corresponding to each power storage block.   The power storage device according to claim 10, further comprising a failure information acquisition unit configured to acquire failure information of at least one of disconnection and short circuit of each of the heat generation groups. The failure information acquisition unit
A plurality of the temperature information acquisition units respectively provided in one of the storage elements included in each of the storage blocks;
The power storage device according to claim 11, further comprising: a plurality of thermal fuses respectively provided on the conductive wires in each of the heat generation groups.   The power storage device according to claim 12, wherein the power storage element provided with the temperature information acquisition unit is a power storage element having the slowest rate of temperature increase among the power storage blocks including the power storage element.   If the controller determines that there is no temperature increase based on the information acquired by the plurality of temperature information acquisition units after instructing the heat generation operation to the plurality of heat generation groups, the controller instructs the stop of the heat generation operation. The power storage device according to claim 12 or 13, wherein a signal to output is output. The failure information acquisition unit
The power storage device according to claim 11, further comprising a plurality of voltage detection units for acquiring information related to voltage values between the heating elements included in each of the heat generation groups.   When the controller determines that the voltage has changed based on the information acquired by the plurality of voltage detection units after instructing the plurality of heat generation groups to perform a heat generation operation, the controller instructs the stop of the heat generation operation. The power storage device according to claim 15, wherein:   A vehicle equipped with the power storage device according to any one of claims 1 to 16.

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