JP6458725B2 - Cooling device for secondary battery - Google Patents

Description

  The present invention relates to a cooling device for a secondary battery.

  A secondary battery such as a chargeable / dischargeable lithium ion battery generates heat as it is charged / discharged. In particular, a secondary battery used for supplying electric power to a motor for driving a wheel mounted on a hybrid vehicle or charging electric power generated when the motor functions as a generator is a charge / discharge current. The amount of heat generated is large because of The secondary battery needs to maintain its performance by suppressing the temperature rise due to heat generation. For this reason, conventionally, a technique for cooling the battery has been proposed.

  In Patent Document 1, when the cooling capacity has decreased due to a change in the cooling capacity of the cooling device over time, the cooling capacity is increased by increasing the number of rotations of the cooling fan, and the planned cooling capacity is maintained. Techniques to make it have been proposed. In the technique of Patent Document 1, how much the number of rotations of the cooling fan is increased is determined by a correction coefficient that is a parameter representing the degree of decrease in cooling capacity. The correction coefficient is a value of 0 to 1.0, and is a parameter that approaches 1.0 when the cooling capacity of the cooling device does not decrease, and approaches 0 as the cooling capacity decreases. The initial value is 1.0. . In the technique of Patent Document 1, the cooling capacity and the heat value of the battery are calculated, the estimated temperature of the battery is calculated from the cooling capacity and the heat value, and the estimated temperature and the actual temperature of the battery detected by the sensor (hereinafter referred to as the battery temperature). The correction coefficient is increased or decreased by a certain amount (hereinafter referred to as correction coefficient update process) at predetermined time intervals based on the comparison with the above. The correction coefficient is a coefficient that is corrected so that the cooling capacity that is theoretically obtained by the equation for calculating the cooling capacity represents the actual cooling capacity that has been lowered due to the change over time. By repeatedly executing the correction coefficient update process, the correction coefficient is changed so that the estimated temperature matches the battery temperature.

The correction coefficient will be further described with reference to FIGS. 7 and 8, at predetermined intervals of time T _P, in the case of performing the correction coefficient update process, estimated temperature, battery temperature, shows a temporal transition of the correction coefficient. T _S is the estimated temperature, and T _B is the battery temperature. E1, E2, E3 is an estimated temperature obtained at each time point every time the time passes _{T P,} R1, R2, R3 is a battery temperature detected at each time point every time the time passes _{T P.} K ₁ in the correction coefficient graph is the value of the correction coefficient at time T0, and is a value larger than 0 and smaller than 1.0. In the correction coefficient update process at each time point, the estimated temperature and the battery temperature are compared. As shown in FIG. 7, when the estimated temperature is lower than the battery temperature, the correction coefficient is set to the first change amount (a constant amount). Decrease. As a result, at the next time point (for example, if the correction coefficient is decreased at time T1, time T2), the cooling capacity is calculated to decrease by the amount of decrease of the correction coefficient, and the estimated temperature is the cooling capacity. Therefore, the estimated temperature changes so as to approach the battery temperature (for example, the battery temperature changes from the time T1 to the time T2 or the cooling is performed). (In some cases, the temperature of the cooling fan's cooling air, which affects the calculation of the capacity, changes. In addition, when the estimated temperature is lower than the battery temperature, the cooling capacity is lower than planned, so by reducing the correction coefficient, the correction coefficient more accurately represents the degree of decrease in cooling capacity. It can also be said. On the other hand, as shown in FIG. 8, when the estimated temperature is higher than the battery temperature, the correction coefficient is increased by the first change amount (a constant amount). As a result, at the next time point (for example, if the correction coefficient is increased at the time point T1, the time point T2), the cooling capacity is calculated to increase by the amount of increase of the correction coefficient, and the estimated temperature is the cooling capacity. Therefore, the estimated temperature changes so as to approach the battery temperature (however, as described above, the estimated temperature may not actually approach). In addition, when the estimated temperature is higher than the battery temperature, the cooling capacity exceeds the schedule, so by increasing the correction coefficient, the correction coefficient more accurately represents the degree of decrease in the cooling capacity. It can also be said.

  By the way, the increase / decrease amount of the correction coefficient at each time point is a constant first change amount which is a minute amount with respect to 1.0, and the correction coefficient is greatly increased / decreased by an amount for matching the estimated temperature with the battery temperature. I don't let you. The purpose of this is to express the degree of decrease in cooling capacity due to deterioration of the cooling device due to long-term use of the cooling device or adhesion of dust. This is because the purpose is not to express the degree of decrease. For example, in the formula for calculating the cooling capacity, the intake air temperature of the cooling air by the cooling fan is taken into account, but depending on the environment in which the cooling device is used, the intake air temperature may change greatly at each time point. The amount of increase or decrease of the correction coefficient at each time point is a fixed amount that is a minute amount with respect to 1.0 so that the influence due to the change of the cooling capacity in such a moment or in a short period is not reflected in the correction coefficient as much as possible. Of the first change amount. Thus, the correction coefficient updated by a minute amount accurately represents the degree of decrease in the cooling capacity of the cooling device itself that has changed due to long-term use.

  When a dustproof filter is attached on the upstream side of the cooling fan, the amount of intake air decreases as the degree of clogging of the filter increases, and the cooling capacity decreases. Therefore, in this case, the correction factor of Patent Document 1 accurately reflects the degree of filter clogging. Specifically, the correction coefficient approaches 1.0 from 0 as the degree of clogging of the filter increases from the state where there is no clogging of the filter. That is, the correction coefficient disclosed in Patent Document 1 is an index indicating the degree of clogging of the filter when a dustproof filter is attached to the upstream side of the cooling fan.

  By the way, Patent Document 2 proposes a technique for detecting a clogging of a filter attached on the upstream side of a cooling fan and warning a user when it is determined that the filter is clogged. In Patent Literature 2, it is determined whether or not the filter is clogged based on the current consumption of the cooling fan.

JP 2013-69470 A JP 2008-136911 A

  In many cases, a cooling fan is used to suppress a temperature rise due to heat generation of the secondary battery, and a dust-proof filter is attached upstream of the cooling fan. When the filter is clogged, the intake amount is reduced and the cooling capacity is lowered. Therefore, when the degree of clogging of the filter increases, the filter needs to be cleaned. Therefore, a filter clogging warning that prompts the user to clean is issued, but in order to give a warning at an accurate timing, it is necessary to accurately grasp the degree of filter clogging.

  In the technique of Patent Document 2, the clogging of the filter is determined based on the current consumption of the cooling fan. However, in this technique, the current consumption of the cooling fan changes only when the degree of filter clogging slightly changes. Therefore, it is impossible to accurately grasp the degree of filter clogging. On the other hand, the correction coefficient of Patent Document 1 can be used as an index indicating the degree of clogging of the filter as described above, and the degree of clogging of the filter can be accurately grasped. Therefore, if the correction coefficient disclosed in Patent Document 1 is used, a filter clogging warning that prompts the user to perform cleaning at an accurate timing can be performed.

  By the way, after the cleaning warning is started, when the filter is cleaned by the user, it is necessary to quickly cancel the warning. That is, it is necessary to quickly detect that cleaning has been performed. However, when the degree of clogging of the filter is grasped using the correction coefficient disclosed in Patent Document 1, it is possible to detect that the correction coefficient has changed due to cleaning and the cleaning has been performed. There are issues that cannot be done promptly. This point will be described with reference to FIGS.

The solid line in FIG. 9 indicates the temporal transition of the correction coefficient. When the time is 0, the correction coefficient is 1.0, indicating that the filter is not clogged. As time elapses, the degree of clogging of the filter increases, so the correction coefficient decreases. 9, the correction coefficient at the PS the time is the time at which was reduced to K _2, starts warning clogging of the filter to promote cleaning the user. If a warning is started, the correction coefficient is to return to K ₁ causes the continuous event, cancels the warning when the correction coefficient is returned to the K _1. 9, after a warning is initiated, since the correction coefficient was cleaned users of filter C they become K _3, since C time turned correction coefficient increases, the correction coefficient is up to K ₁ The warning is canceled when it returns. Since the degree of clogging of the filter reaches the level that requires cleaning over several months or years, for example, the time from time 0 to time PS in FIG. 9 is a long time of several months or years. Therefore, a long interval of about several minutes is sufficient for updating the correction coefficient. Further, as described above, the amount of change at one time needs to be a minute amount so that the influence due to the instantaneous or short-term change in the cooling capacity is not reflected in the correction coefficient as much as possible. However, when the correction coefficient update interval is long and the amount of change at one time is small, the time T _{C_OFF} from the time point C at which cleaning is performed until the warning is canceled is long as shown in FIG. There is a problem that becomes. In FIG. 9, for the convenience of the drawing, the _{TC_OFF} time is drawn longer, and the same _applies to FIGS. 6 and 10 described later.

For example, by shortening the update interval of the correction coefficient (for example, updating in units of 1 second), the time of _{TC_OFF} can be shortened, but it takes several months or several months to reach a state where the filter needs to be cleaned. It takes years and the time of _{TC_OFF} is only a minute time from the whole. Therefore, it is not necessary to shorten the update interval in many times other than the time of _{TC_OFF.} If the update interval is shortened, power consumption of the control unit is wasted in many times. In addition, if the update interval of the correction coefficient is shortened, the influence due to the instantaneous or short-term change in the cooling capacity as described above is easily reflected in the correction coefficient, and the correction coefficient becomes clogged with the filter. There also arises a problem that the degree cannot be expressed accurately.

In addition, for example, the time of _{TC_OFF} can be shortened by increasing the amount of change of the correction coefficient once. However, as described above, the influence due to the instantaneous or short-term change in the cooling capacity. Is easily reflected in the correction coefficient, and the correction coefficient does not accurately represent the degree of clogging of the filter. FIG. 9 shows a case where the amount of change of the correction coefficient once is the first amount of change, and FIG. 10 shows a case where the amount of change of one time is 10 times (first change amount × 10). It is shown. Further, FIG. 11, the clogging degree of the filter is when a was the state corresponding to K ₂ of the correction coefficient is a probability distribution of values the correction coefficient can take. As shown in FIG. 11, if a single change in the amount of correction factors of the first variation, the value of the correction coefficient is never becomes a value largely deviated from K _2, the change in one correction factor If the amount of (first change amount × 10), the value of the correction coefficient may become a value deviated largely from the K _2. The dashed line in FIGS. 9 and 10 indicates the value when the correction coefficient is most deviated downward with respect to the ideal correction coefficient value (solid line), and the double dotted line indicates the value of the ideal correction coefficient. A value when the correction coefficient is most deviated upward with respect to (solid line) is shown. As shown in FIG. 10, when the amount of change at one time is increased, the correction coefficient may deviate significantly from the ideal correction coefficient value (solid line). For example, the original warning is started. There is a possibility that the warning is started at the PB time or PU time, which is far from the PS time as the timing. That is, there is a problem that a filter clogging warning cannot be started at an accurate timing.

As described above, the problem that the time _{TC_OFF} from when the filter is cleaned to when the warning is canceled becomes long cannot be easily solved. Therefore, the present invention calculates the estimated temperature of the secondary battery using the cooling capacity and the calorific value of the secondary battery, compares the calculated estimated temperature with the battery temperature detected by the battery temperature sensor, and compares the results. In accordance with, the correction coefficient in the formula for calculating the cooling capacity is increased or decreased, and the correction coefficient is changed so that the estimated temperature matches the battery temperature by performing correction coefficient update processing at predetermined time intervals, A cooling device for a secondary battery that uses the correction coefficient to grasp the degree of clogging of the filter of the cooling fan. After the degree of clogging of the filter increases and a filter clogging warning is started, the filter is An object of the present invention is to provide a cooling device for a secondary battery that promptly cancels a warning when cleaning is performed.

  The cooling device for a secondary battery of the present invention includes a cooling fan for cooling the secondary battery, a dustproof filter for the cooling fan, a battery temperature sensor for detecting the temperature of the secondary battery, the cooling capacity, The estimated temperature of the secondary battery is calculated using the calorific value of the secondary battery, and the correction coefficient for correcting the cooling capacity to represent the actual capacity that has changed with time in the formula for calculating the cooling capacity is changed. A control unit, wherein the control unit calculates the estimated temperature, compares the estimated temperature with a battery temperature detected by the battery temperature sensor, and the first state is lower than the battery temperature. In the case of the above, the correction coefficient is decreased by a certain amount, and in the second state where the estimated temperature is higher than the battery temperature, the correction coefficient is increased by the certain amount or a larger amount than the certain amount. Correction factor By performing a new process at a predetermined time interval, the correction coefficient is changed so that the estimated temperature matches the battery temperature, and when the correction coefficient falls below a warning threshold, the notification unit A warning for filter clogging is performed, and when the correction coefficient is not less than the warning threshold value and not less than a warning release threshold value that is greater than the warning threshold value, the notification unit is caused to cancel the warning, and the predetermined time In the correction coefficient updating process performed at intervals, when the second state continues, the correction coefficient is increased by an amount larger than the predetermined amount.

  According to the cooling device for a secondary battery of the present invention, when the filter is cleaned by the user after starting the filter clogging warning, the warning can be quickly released.

It is a block diagram which shows the outline of a structure of the cooling device for secondary batteries. It is a flowchart regarding control of a correction coefficient update process and warning. It is a flowchart regarding the increase process of a correction coefficient among correction coefficient update processes. It is a graph which shows an example of a change of presumed temperature and battery temperature, and a graph which shows an example of a change of a correction coefficient. It is a graph which shows an example of change of a correction coefficient after cleaning of a filter. It is a graph which shows an example of the change of the correction coefficient in a long period. It is a graph which shows an example of the change of the estimated temperature and battery temperature of a prior art, and an example of a change of a correction coefficient. It is a graph which shows an example of the change of the estimated temperature and battery temperature of a prior art, and an example of a change of a correction coefficient. It is a graph which shows an example of the change of the correction coefficient in the long period of a prior art. It is a graph which shows an example of the change of the correction coefficient in a long period when the variation | change_quantity of the correction coefficient of the prior art is enlarged. It is a graph which shows the difference in the probability distribution of the correction coefficient by the difference in the variation | change_quantity of the correction coefficient of 1 time of a prior art.

  A cooling device 100 for a secondary battery according to an embodiment will be described with reference to the drawings. FIG. 1 is a configuration diagram showing an outline of the configuration of a cooling device 100 for a secondary battery. As shown in the figure, a cooling device 100 for a secondary battery according to the present embodiment includes a case 30 that forms a cooling air passage for cooling the chargeable / dischargeable secondary battery 20, and an inlet for the cooling air of the case 30. A filter 1 attached to the intake port 25, an intake air temperature sensor 41 for detecting the intake air temperature of the cooling air attached in the vicinity of the intake port 25, a cooling fan 10 attached downstream of the filter 1, A battery temperature sensor 42 that detects a battery temperature that is the temperature of the secondary battery 20, a current sensor 45 that detects a charge / discharge current I of the secondary battery 20, a control unit 50 that controls the entire apparatus, and a filter 1 that is clogged. And a notifying unit 80 that issues a warning for prompting the user to clean when the degree of cleaning is in a state that requires cleaning.

  The secondary battery cooling device 100 is mounted on a hybrid vehicle. The secondary battery 20 is used to supply electric power to a wheel driving motor or to charge electric power generated when the motor functions as a generator, and a device for cooling the secondary battery 20 has two This is a cooling device 100 for a secondary battery.

  The notification unit 80 is a lamp, and the lamp is turned on when a warning is given, and the lamp is turned off when the warning is not given. However, the lighting may be reversed and the lighting may be reversed. The notification unit 80 may be in the form of a liquid crystal display or a speaker instead of a lamp, and the form is not limited. When the alerting | reporting part 80 is a liquid crystal display, the form which displays a warning on a liquid crystal display can be considered. Moreover, when the alerting | reporting part 80 is a speaker, the form which conveys a warning with an audio | voice is considered.

  The control unit 50 includes a CPU 51, a ROM 52 that stores a program executed by the CPU 51, a RAM 53 that stores temporarily calculated results, and an input / output port (not shown). The controller 50 receives the intake air temperature from the intake air temperature sensor 41, the battery temperature from the battery temperature sensor 42, the value of the charge / discharge current I of the secondary battery 20 from the current sensor 45, and the like via the input port. ing. Further, a signal for instructing a warning to the notification unit 80 is output from the control unit 50 via the output port.

  Next, an outline of processing executed by the control unit 50 will be described. The control unit 50 determines in advance a correction coefficient for correcting the cooling capacity that is theoretically determined by an expression for calculating the cooling capacity (formula (Equation 2) to be described later) to represent the actual cooling capacity that has decreased due to a change with time. Update at specified time intervals. In the present embodiment, this correction coefficient indicates the degree of clogging of the filter 1. The correction coefficient is a value between 0 and 1.0, and is 1.0 when the filter 1 is not clogged, approaches 0 as the degree of clogging of the filter 1 increases, and the initial value is 1.0. The control unit 50 calculates the cooling capacity and the heat generation amount of the secondary battery 20, calculates the estimated temperature of the secondary battery 20 using the calculated cooling capacity and heat generation amount, and calculates the estimated temperature and the battery temperature sensor 42. In the first state where the estimated temperature is lower than the battery temperature, the correction coefficient is decreased by a first change amount (a constant amount), and the estimated temperature is higher than the battery temperature. In the case of the state, the correction coefficient updating process for increasing the correction coefficient by the first change amount (a constant amount) or the second change amount larger than the first change amount is performed at predetermined time intervals. . The difference between the correction coefficient update process of the technique of Patent Document 1 as the prior art and the correction coefficient update process of the present embodiment is the point related to the increase of the correction coefficient in the second state (S110 in FIG. 2 described later). is there.

  When the correction coefficient is equal to or less than the warning threshold, the control unit 50 determines that the degree of clogging of the filter 1 has reached a state that requires cleaning, and causes the notification unit 80 to start a warning. In addition, after the control unit 50 causes the notification unit 80 to start a warning, when the correction coefficient becomes equal to or greater than the warning release threshold that is greater than or equal to the warning threshold, the filter 1 is cleaned by the user. Judgment is made and the warning unit 80 is made to cancel the warning.

  Next, correction coefficient update processing and warning control executed by the control unit 50 according to the present embodiment will be described in detail with reference to FIGS. FIG. 2 is a flowchart regarding correction coefficient update processing and warning control, and FIG. 3 is a flowchart in which “correction coefficient increase processing” of S110 in FIG. 2 is extracted and described. The control unit 50 updates the correction coefficient by executing the flow shown in FIG. 2 at predetermined time intervals. In the present embodiment, among the steps shown in FIG. 2, the steps excluding the steps (S118 to S126) relating to the warning control are correction coefficient update processing.

  When the flow of FIG. 2 is started, the control unit 50 calculates an estimated temperature of the secondary battery 20 (S100). The estimated temperature is calculated using a plurality of mathematical formulas shown below. First, the calorific value HW [W] of the secondary battery 20 is calculated based on the following (Equation 1).

Calorific value HW = I ² × R (T _B ) (Equation 1)

In the equation (1), “I” is the charge / discharge current I [A] of the secondary battery 20 detected by the current sensor 45, and “T _B ” is the battery temperature detected by the battery temperature sensor 42. [C] and “R (T _B )” is the internal resistance [Ω] of the secondary battery 20 according to the battery temperature. Next, the cooling capacity CW [W] is obtained based on the following (Equation 2).

Cooling capacity CW = K _F (p) × (T _B −T _C ) × Q × bb (Equation 2)

In the equation (2), “p” is atmospheric pressure [kPa], “K _F (p)” is a cooling performance coefficient, and “T _B ” is the battery temperature [° C.] detected by the battery temperature sensor 42. a], "T _C" is the intake air temperature detected by the intake air temperature sensor 41 [° C.], "Q" is the amount of cooling air [m ³ / h], "bb" is "previous correction coefficient" It is. “Previous correction coefficient” is the value of the correction coefficient at the end of the previous cycle (the time when the flow in FIG. 2 was executed last time). The cooling air volume Q [m ³ / h] is obtained by the following equation (3).

  Cooling air volume Q = a × N (Equation 3)

  In the formula (3), “N” is the cooling fan rotation speed [rpm], and “a” is a coefficient for converting the cooling fan rotation speed into the cooling air volume. Next, the estimated temperature [° C.] is obtained based on the following equation (4).

Estimated temperature T _S = previous T _B + γ × (heat generation amount HW−cooling capacity CW) × dT (Equation 4)

In equation (4), "the last T _B" is the battery temperature detected in the period of one time before (when previous run the flow of FIG. 2). Γ is a coefficient for converting the heat quantity [J] into the temperature [° C.], and dT is the period [sec]. dT is an interval at which the flow of FIG. 2 is executed, and is a predetermined time in this embodiment.

  Thus, the estimated temperature is calculated using the cooling capacity corrected by the correction coefficient in the previous cycle and the heat generation amount of the secondary battery 20.

  Returning to FIG. Since the estimated temperature is calculated in S100, it is next determined whether the calculated estimated temperature and the battery temperature of the secondary battery 20 detected by the battery temperature sensor 42 are different or the same (S104). If they are the same (S104: No), it is determined that there is no need to change the value of the correction coefficient, “STAY” is input to the variable “correction direction” (S116), and the flow of FIG. 2 ends. Even if the estimated temperature and the battery temperature are not the same, it may be determined that the estimated temperature and the battery temperature are the same if the difference between the estimated temperature and the battery temperature is within a predetermined temperature. If the estimated temperature and the battery temperature are different (S104: Yes), it is determined that the correction coefficient value needs to be changed, and the process proceeds to S106 where the estimated temperature and the battery temperature are compared. In S106, when the estimated temperature is lower than the battery temperature (S106: No), the cooling capacity is below the schedule, so the process proceeds to S108 where the correction coefficient is decreased. In S108, the correction coefficient is reduced by a first change amount that is a fixed amount. When the correction coefficient is decreased in S108, the process proceeds to S114, and “DOWN” is input to the variable “correction direction” (S114). And it is discriminate | determined whether a correction coefficient is below a warning threshold value (S120). S120 is to determine whether or not the degree of clogging of the filter 1 has reached a state that requires cleaning. When the correction coefficient is equal to or less than the warning threshold (S120: Yes), it is determined that the degree of clogging of the filter 1 has reached a state where cleaning is necessary, and the notification unit 80 issues a warning about clogging of the filter 1. (S122). Specifically, the lamp is turned on (S122).

  In S106 of FIG. 2, when the estimated temperature is higher than the battery temperature (S106: Yes), the cooling capacity is higher than planned, so the process proceeds to “Correction coefficient increasing process” of S110. In S110, the process of increasing the correction coefficient is performed contrary to S108, but the specific processing content will be described later with reference to FIG. After increasing the correction coefficient in S110, “UP” is input to the variable “correction direction” (S112), and the process proceeds to S118. In S118, it is determined whether or not the notification unit 80 is in a state where a warning of clogging of the filter 1 is performed, specifically, whether or not the lamp is lit (S118). If the lamp is on (S118: Yes), it is determined whether or not the correction coefficient is equal to or greater than the warning cancellation threshold (S124). In step S124, it is determined that the user has cleaned the filter 1 in a state in which the notification unit 80 performs a warning, and determines whether or not the warning can be canceled. If the correction coefficient is equal to or greater than the warning cancellation threshold (S124: Yes), it is determined that the filter 1 has been cleaned by the user, and the notification unit 80 releases the warning (S126). Specifically, the lamp is turned off (S126).

  The correction coefficient at the time when the flow of FIG. 2 is completed is used in the above-described equation (2) in the calculation of the estimated temperature of S100 in the next period (the next execution of the flow of FIG. 2). The correction coefficient for the next period is updated using the estimated temperature. That is, the correction coefficient forms a feedback loop, and if the correction coefficient is far from the value that should be originally obtained, the estimated temperature of the next cycle is calculated (S100), and the estimated temperature is compared with the battery temperature (S104, In S106), it appears, and the correction coefficient is corrected so that the estimated temperature approaches the battery temperature, so that the correction coefficient converges to a value that should be originally obtained. That is, the correction coefficient accurately represents the degree of decrease in the cooling capacity of the cooling device 100 for the secondary battery, and in this embodiment, the degree of clogging of the filter 1 is accurately represented. Therefore, a warning that prompts the user to clean the filter 1 can be given at an accurate timing.

  Next, the “correction coefficient increasing process” in S110 of FIG. 2 will be described. In the process of S110, the process of increasing the correction coefficient is performed contrary to the process of S108, but in addition to the process of increasing the correction coefficient by the first change amount that is a constant amount, a change larger than the first change amount is performed. Including a process of increasing the correction coefficient by the second change amount which is a quantity. As described above, the reason for including the process of increasing the correction coefficient by the second change amount larger than the first change amount is that the filter 1 is cleaned by the user in a state in which the filter 1 is clogged. This is to promptly cancel the warning when it is released. That is, when the filter 1 is cleaned, the correction coefficient is increased by a second change amount that is larger than the first change amount, and the correction coefficient is quickly made equal to or higher than the warning cancellation threshold value in S124 of FIG. Then cancel the warning promptly.

  FIG. 3 is a flowchart in which “the correction coefficient increasing process” in S110 of FIG. 2 is extracted and described. When the flow of FIG. 3 is started, it is determined whether or not the “previous correction direction” is “UP” (S200). The “previous correction direction” is the direction that was input to the variable “correction direction” at the end of the previous cycle. The “previous correction direction” indicates whether the correction coefficient has been decreased (DOWN), increased (UP), or maintained (STAY) in the previous cycle. When the “previous correction direction” is not “UP” (S200: No), 0 is input to the variable “increase speed” (S202). Note that the value of the variable “correction direction” in the initial state where the flow shown in FIGS. 2 and 3 has never been executed is “STAY”, and the value of the variable “increase speed” is 0. After S202, the process proceeds to S204 to increase the correction coefficient. The increase amount (change amount) of the correction coefficient in S204 is a first change amount that is a constant amount, and the change amount of the correction coefficient is the same as S108 in FIG. In S204, after the correction coefficient is increased, the “correction coefficient increase process” is ended.

  Next, a case where the “previous correction direction” is “UP” in S200 (S200: Yes) will be described. When the “previous correction direction” is “UP” (S200: Yes), the process proceeds to S206. In S206, 1 is added to the “previous increase speed” and the variable “increase speed” is input. This “previous increase rate” is a value that has been input to the variable “increase rate” at the end of the previous cycle. Here, it is assumed that the “previous increase rate” is zero. Accordingly, 1 is input to the variable “increase speed”. Next, it progresses to S208 and calculates 2nd variation | change_quantity. In S208, calculation of the power of α (increase in speed), which is an exponential function with α (where α> 1) as the base, is performed. Since the current variable “increasing speed” is 1, α is raised to the first power, which is multiplied by the first change amount, which is a constant amount, to calculate the second change amount. Since α is a value larger than 1, the second change amount is larger than the first change amount. Next, in S210, the second change amount is added to the previous correction coefficient, and the correction coefficient is updated. Next, the process proceeds to S212. Here, “1”, which is the value of the current variable “increase speed”, is less than the speed threshold (S212: No), and “correction coefficient increase process” is ended. Thus, when the “previous correction direction” is “UP” (S200: Yes), the value of the variable “increase speed” is increased (S206). The variable “increasing speed” represents how many times the cycle in which the variable “correction direction” is “UP” is continued. The greater the number of consecutive times, the greater the value of the variable “increasing speed”. When the value of the variable “increasing speed” increases, the value of α (increasing speed), which is an exponential function calculation based on α, increases, so the second change amount increases (S208), and The increase amount (change amount) of the correction coefficient is increased (S210). The period in which the variable “correction direction” is “UP” is the period in which the estimated temperature is determined to be higher than the battery temperature (S106 in FIG. 2), and is the period in which the cooling capacity is determined to exceed the schedule. . If the cycle is continuous, there is a high possibility that the filter 1 has been cleaned by the user and the cooling capacity has rapidly increased. Therefore, when the period in which the variable “correction direction” is “UP” continues, the correction coefficient increase amount (change amount) increases exponentially according to the number of consecutive times, and the correction coefficient increases rapidly. ing. As a result, the correction coefficient can be quickly increased to the warning cancellation threshold value or more (S124: Yes in FIG. 2), and the clogging warning of the filter 1 can be quickly released.

  Further, in this embodiment, when the estimated temperature is determined to be higher than the battery temperature (S106: Yes in FIG. 2), the variable “increased speed” reaches the speed threshold value, and the correction is performed. The coefficient can be increased at a stretch to the jump value. This is S212 and S214 in FIG. 3, and when the value of the variable “increase speed” is equal to or higher than the speed threshold and the correction coefficient is less than the jump value (S212: Yes), regardless of the value of “previous correction coefficient”. The correction coefficient value is set to the jump value. Note that the jump value is slightly larger than the warning threshold value (S120 in FIG. 2) that is the value of the correction coefficient for starting the warning, and is smaller than the warning cancellation threshold value (S124 in FIG. 2). When the value of the variable “increased speed” increases and reaches the speed threshold value, the possibility that the filter 1 has been cleaned by the user is very high. Therefore, the correction coefficient is increased to the jump value all at once. Thereby, the warning of clogging of the filter 1 can be released more quickly. Note that the jump value is set to a warning cancellation threshold value (S124 in FIG. 2) at which the warning is canceled, so that the correction coefficient is raised to the warning cancellation threshold value at once and the warning is immediately released (S126 in FIG. 2). Is also possible. However, in this embodiment, there is a possibility that the filter 1 is not cleaned by the user. Therefore, the correction coefficient value that is increased at a stroke is not set as the warning cancellation threshold value, and the warning is not canceled immediately. I have to.

4 and 7 are a graph showing an example of changes in estimated temperature and battery temperature and a graph showing an example of changes in correction coefficients in this embodiment. FIG. 7 shows a case where the first state where the estimated temperature is lower than the battery temperature is continuous, and FIG. 4 shows a case where the second state where the estimated temperature is higher than the battery temperature is continuous. However, various patterns may actually exist such as when the first state and the second state occur alternately or when the estimated temperature and the battery temperature are the same. In the present embodiment, as shown in FIG. 7, in the first state, the correction coefficient decreases by a first change amount that is a constant amount. Even when the first state continues, the reduction amount (change amount) of the correction coefficient does not change with the first change amount. Such a change in the correction coefficient when the estimated temperature is lower than the battery temperature is the same as the change in the correction coefficient in the technique of Patent Document 1 which is a conventional technique. On the other hand, as shown in FIG. 4, when the estimated temperature is higher than the battery temperature in the second state, the correction coefficient increases, but when the second state continues, the correction coefficient is the first change amount. The increase amount (change amount) of the correction coefficient is an exponent, such as an increase of (first change amount × α) in the next cycle and an increase of (first change amount × α ² ) in the next cycle. It grows functionally. If the period of the first state is not continuous and the period of the first state is in between, or if the period of the state in which the estimated temperature is the same as the battery temperature is in between, The increase amount (change amount) of the correction coefficient in the period of the second state becomes the first change amount.

FIG. 5 shows a change in the correction coefficient when the second state in which the estimated temperature is higher than the battery temperature continues further than in FIG. The warning threshold value that is the value of the correction coefficient for starting the warning is indicated as K ₂ , and the warning cancellation threshold value that is the value of the correction coefficient for releasing the warning is indicated as K ₁ . In Figure 5, at time point C the value of the correction coefficient is K _3, shows a case where the user has to clean the filter 1. When cleaning is performed, the cooling capacity is rapidly increased, so that the cycle of the second state, in which the estimated temperature is higher than the battery temperature, continues, and the correction coefficient increases as shown in FIG. JP in FIG. 5 indicates that the correction coefficient has been updated to the jump value in S214 in FIG. In FIG. 5, after 10 cycles from the time point C at which the filter 1 is cleaned, the correction coefficient value exceeds the warning cancellation threshold value and reaches (K ₁ + V ₁ ), and the warning can be canceled.

FIG. 6 is an example of a change in the correction coefficient over a long period of the present embodiment, and FIG. FIG. 9 shows that the amount of change in one cycle is fixed to the first amount of change which is a constant amount regardless of whether or not the second state in which the estimated temperature is higher than the battery temperature is continuous. It is an example of the change of the correction coefficient in a long period of the case. As shown in FIGS. 6 and 9, the time T _{C_OFF} from when the user cleans the filter 1 until the warning is canceled is shorter in FIG. 6 of the present embodiment than in FIG. 9 of the prior art. Become.

  The cooling device 100 for the secondary battery according to the embodiment described above calculates the cooling capacity and the calorific value of the secondary battery 20, and uses the calculated cooling capacity and the calorific value to calculate the estimated temperature of the secondary battery 20. The calculated estimated temperature is compared with the battery temperature detected by the battery temperature sensor 42. In the first state where the estimated temperature is lower than the battery temperature, the correction coefficient is decreased by a certain amount, and the estimated temperature becomes the battery temperature. If the second state is higher, the correction coefficient is updated at a predetermined time interval in which the correction coefficient is increased by a certain amount or by a larger amount than the certain amount. In the correction coefficient updating process performed at predetermined time intervals, when the second state continues, the correction coefficient is not increased by a fixed amount but by an amount larger than the fixed amount. Therefore, according to the cooling device 100 for the secondary battery of the embodiment, when the filter 1 is cleaned by the user, the second state is set in the correction coefficient updating process performed at a predetermined time interval. Since the possibility of being continuous is very high, the correction coefficient increases greatly in a short time. As a result, when the filter 1 is cleaned by the user after the warning about the clogging of the filter 1 is started, the correction coefficient reaches the warning release threshold for releasing the warning in a short time. It can be canceled.

  In the cooling device 100 for the secondary battery according to the embodiment described above, when the variable “increase rate” reaches the speed threshold, that is, the second state where the estimated temperature is higher than the battery temperature is the number of times of the speed threshold. When the correction coefficient is less than the jump value (S212 in FIG. 3: Yes), the correction coefficient is increased to the jump value all at once (S214 in FIG. 3). However, this process (S212, S214 in FIG. 3) is not necessarily required and may be omitted.

  In the cooling device 100 for the secondary battery of the embodiment described above, the cooling capacity is further decreased as the correction coefficient approaches 1.0 from 0, that is, the degree of clogging of the filter 1 is high. Was represented. However, it may be expressed as the correction coefficient approaches 0 to 1.0. In that case, when the estimated temperature is lower than the battery temperature in the first state, the correction coefficient is increased by a certain amount, and when the estimated temperature is higher than the battery temperature in the second state, the correction coefficient is increased by a certain amount, or , It will be reduced by an amount greater than a certain amount. Further, in the correction coefficient update process performed at predetermined time intervals, when the second state continues, the correction coefficient is decreased by an amount larger than a certain amount. Then, when the correction coefficient is equal to or higher than the warning threshold, a warning of clogging of the filter 1 is started, and when the correction coefficient is equal to or higher than the warning threshold and lower than the warning cancellation threshold, the warning is canceled. It will be.

  DESCRIPTION OF SYMBOLS 1 Filter, 10 Cooling fan, 20 Secondary battery, 25 Intake port, 26 Exhaust port, 30 Case, 41 Intake temperature sensor, 42 Battery temperature sensor, 45 Current sensor, 50 Control part, 51 CPU, 52 ROM, 53 RAM, 80 Notification unit, 100 Cooling device for secondary battery.

Claims (1)

A cooling fan for cooling the secondary battery;
A dustproof filter for the cooling fan;
A battery temperature sensor for detecting the temperature of the secondary battery;
A correction for calculating the estimated temperature of the secondary battery using the cooling capacity and the calorific value of the secondary battery, and correcting the cooling capacity to represent the actual capacity that has changed over time in the formula for calculating the cooling capacity. A control unit for changing the coefficient,
The controller is
The estimated temperature is calculated, and the estimated temperature is compared with the battery temperature detected by the battery temperature sensor. When the estimated temperature is lower than the battery temperature, the correction coefficient is decreased by a certain amount. A correction coefficient update process for increasing the correction coefficient by the fixed amount or an amount larger than the fixed amount when the estimated temperature is higher than the battery temperature. By changing the correction coefficient so that the estimated temperature matches the battery temperature,
When the correction coefficient is equal to or lower than the warning threshold, the notification unit is caused to warn of clogging of the filter, and when the correction coefficient is equal to or higher than the warning cancellation threshold greater than the warning threshold. Causes the notification unit to cancel the warning,
In the correction coefficient updating process performed at the predetermined time interval, when the second state continues, the correction coefficient is increased by an amount larger than the certain amount.
A cooling device for a secondary battery.

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