JP6631493B2 - In-vehicle battery pack cooling system - Google Patents

Description

  The present invention relates to a vehicle-mounted battery pack cooling system.

  A hybrid vehicle or an electric vehicle using a rotating electric machine as a driving source is equipped with a battery pack (secondary battery) as a power supply and a cooling system therefor. The cooling system is provided with a cooling fan that takes in air in the vehicle compartment as cooling air and sends it to the battery pack.

  For example, in Patent Literature 1, the presence or absence of clogging of a filter provided at a cooling air intake port is estimated based on the total amount of air supplied to a battery pack when a cooling fan is driven. In Patent Document 2, the operation of the cooling fan is controlled so that the operating noise of the cooling fan is relatively small with respect to background noise such as vehicle speed, engine noise, and air conditioning noise.

JP-A-2014-07182 JP 2007-331737 A

  By the way, in order to control the cooling efficiency of the battery pack and the like, the temperature of the intake air is checked. For example, when the temperature of the intake air taken in from the vehicle interior is equal to or higher than the temperature of the battery pack, the cooling fan is stopped. When the cooling fan is started from a stopped state, a delivery process of sending out (exhausting) the stagnant air in the intake passage is performed before checking the temperature of the intake air taken in. The intake flow path refers to a flow path (such as a duct) from the intake port of the cabin air to the battery pack via the cooling fan.

  Regarding the process of sending out the stagnant air before the temperature check, the cooling fan is operated at a predetermined low rotational speed (for example, the minimum rotational speed) in consideration of the case where the vehicle interior is in a quiet environment such as when the vehicle is stopped. The pump is driven to rotate at a constant speed and sends out stagnant air while minimizing noise. In addition, the low rotation speed constant drive is continued until a time when the staying air is sent out from the intake passage and it is considered that the vehicle interior air is sufficiently introduced into the intake passage.

  As described above, in sending out the staying air in the intake passage, conventionally, the cooling fan is driven at a constant low rotation speed, and the driving period is also until after the staying air is sent out from the intake passage, in other words, It may continue until the volume of air sent out by the cooling fan exceeds the volume (volume) of the intake passage. As a result, a long time is spent in the process of sending out the stagnated air, and the standby time until the intake air temperature check and the subsequent cooling of the battery pack is prolonged, which may delay the cooling of the battery pack. Accordingly, the present invention provides an on-board battery that allows the air remaining in the cooling passage to be sent out more quickly than before, thereby suppressing the intake air temperature earlier than before while suppressing discomfort to the occupant due to the noise caused by driving the cooling fan. It is an object to provide a pack cooling system.

  The in-vehicle battery pack cooling system according to the present invention is provided in a cooling fan that takes in air in the vehicle compartment and sends it to the battery pack, and is provided in an intake passage from the air intake port in the vehicle compartment to the battery pack through the cooling fan. An intake air temperature sensor, a cooling fan control unit that performs variable control to change the number of rotations of the cooling fan according to the temperature of the battery pack within a range equal to or less than the maximum allowable number of rotations of the cooling fan determined according to the vehicle speed, The cooling fan includes an air volume integrating unit that calculates the air volume of the cooling fan based on the number of rotations of the cooling fan and calculates a volume of air sent by the cooling fan, and a cooling fan drive determination unit. The cooling fan drive determination unit obtains the intake air temperature from the intake air temperature sensor when the outgoing air volume is equal to or greater than the volume from the air intake port to the intake air temperature sensor in the intake air passage, and the intake air temperature is When the temperature is equal to or higher than the temperature, a cooling fan drive stop command is output to the cooling fan control unit.

  According to the present invention, by variably controlling the cooling fan, it is possible to obtain a larger air volume than in the related art that has performed the constant control of the minimum rotation speed, and therefore, it is possible to reduce the delivery of the stagnant air in the intake passage compared to the related art. Can be done early. In this variable control, the number of revolutions of the cooling fan is limited to a maximum allowable number of revolutions or less determined according to the vehicle speed. That is, the driving noise of the cooling fan is masked by so-called road noise. This makes it possible to suppress the occupant's discomfort caused by the driving noise of the cooling fan. In addition, according to the present invention, the volume of air sent out by the cooling fan is measured, and when the volume becomes equal to or more than the volume (volume) from the air intake port to the intake air temperature sensor in the intake air flow path, the intake air temperature check is performed. In this manner, the intake air temperature can be quickly checked by reducing the volume of air to be sent required from the start of the cooling fan to the temperature check to the minimum necessary.

It is a block diagram which illustrates the battery pack cooling system concerning this embodiment, and the principal part of the vehicle carrying this. It is a figure which illustrates the in-vehicle layout of a battery pack and its cooling system. It is a figure which illustrates a vehicle speed-maximum permissible rotation speed map. 5 is a flowchart illustrating a cooling fan drive determination flow according to the embodiment. It is a figure which illustrates a rotation speed-air volume conversion map. It is a figure explaining variable control of a cooling fan.

  FIG. 1 illustrates the configuration of a battery pack cooling system according to the present embodiment and a vehicle equipped with the same. Note that, for simplicity of illustration, in FIG. 1, illustration of components having low relevance to the battery cooling system according to the present embodiment is omitted as appropriate. The arrow lines in FIG. 1 represent signal lines.

  The vehicle shown in FIG. 1 is a hybrid vehicle that uses an internal combustion engine and a rotating electric machine as driving sources. However, the vehicle on which the battery pack cooling system according to the present embodiment is mounted is not limited to this. In short, any vehicle may be used as long as it has a rotating electric machine as a drive source and a large-capacity battery pack for supplying electric power thereto. For example, the cooling system according to the present embodiment may be mounted on an electric vehicle or a fuel cell vehicle. .

  In the vehicle (hybrid vehicle) shown in FIG. 1, DC power output from battery pack 10 is boosted by a step-up / step-down DC / DC converter (not shown), is orthogonally transformed by an inverter, and supplied to a load such as a rotating electric machine. You.

  The vehicle shown in FIG. 1 is provided with a branch circuit that branches off from a circuit (high-voltage circuit) connecting the battery pack 10 and a load and is connected to the step-down DC / DC converter 12. The DC power stepped down by the step-down DC / DC converter 12 is orthogonally converted by the fan inverter 14. The converted AC power is supplied to the fan motor 16. The cooling fan 18 is driven to rotate by the fan motor 16, and cooling air is taken in.

<Configuration of battery pack cooling system>
The battery pack cooling system according to the present embodiment includes a battery pack 10, a cooling fan 18, an intake passage 20, a fan motor 16, a fan inverter 14, and a control unit 22. Each component of the battery pack cooling system except for at least the control unit 22 is disposed below the rear seat 23 of the vehicle, for example, as shown in FIG.

  The battery pack 10 is composed of a secondary battery such as a nickel metal hydride or lithium ion battery. For example, the battery pack 10 is configured by a stack (stack) in which a plurality of battery cells (unit cells) of about 1 to 5 V are stacked. The battery pack 10 is housed in the cover 24. The cover 24 has a supply port 26 and a discharge port 28 for cooling air. As will be described later, the intake air (cooling air) sent from the cooling fan 18 is taken into the cover 24 from the supply port 26 and the battery pack 10 is air-cooled. The cooled air is discharged from the outlet 28.

  The intake passage 20 is an intake passage from the air intake port 30 in the vehicle compartment to the supply port 26 of the battery pack 10 via the cooling fan 18. The intake passage 20 includes an intake duct 32, a casing 35 of the cooling fan 18, and a connection duct 34. The intake duct 32 connects the air intake port 30 in the passenger compartment to the intake port 36 provided in the casing 35 of the cooling fan 18. The intake port 30 of the intake duct 32 may be provided with a filter 38 for removing dust. As illustrated in FIG. 2, the intake port 30 and the filter 38 are provided on a side of a cover 39 that covers a lower portion of the rear seat 23 of the vehicle. Returning to FIG. 1, the connection duct 34 connects the outlet 40 of the cooling fan 18 to the supply port 26 of the cover 24 of the battery pack 10.

  The cooling fan 18 is a blower that sends cooling air to the battery pack 10. The cooling fan 18 is composed of, for example, a sirocco fan (multi-blade fan). The cooling fan 18 takes in the air in the vehicle cabin through the intake duct 32 and sends the air (intake air) taken in through the connection duct 34 to the battery pack 10.

  The fan motor 16 drives the cooling fan 18 to rotate. The fan motor 16 is composed of, for example, a three-phase brushless motor having a rated voltage of 14 [V]. A drive voltage (three-phase voltage) is applied to the fan motor 16 from the fan inverter 14, whereby the fan motor 16 is driven to rotate. The rotor position of the fan motor 16 is detected by the position sensor 42 and is used for feedback control described later. In the following, for easy understanding, it is assumed that the rotation speed [rpm] of the fan motor 16 and the rotation speed [rpm] of the cooling fan 18 are the same.

  The fan inverter 14 converts DC power supplied from the battery pack 10 via the step-down DC / DC converter 12 or DC power directly supplied from a sub-battery (not shown) into AC power, and converts the AC power into fan power. To supply. The fan inverter 14 includes a plurality of switching elements, and on / off operations of these switching elements are controlled based on a PWM control signal sent from the cooling fan drive control unit 22A of the control unit 22.

  The control unit 22 controls devices in the vehicle including the battery pack cooling system. The control unit 22 is composed of, for example, a computer, and includes a CPU as an arithmetic circuit and a memory as a storage device. The memory includes a volatile memory such as an SRAM and a nonvolatile memory such as a ROM and a hard disk.

  The memory stores a control program for controlling the cooling fan 18, a program for executing an intake air temperature detection flow described later, and the like. When the CPU executes this program, a plurality of functional units are configured in the control unit 22. Specifically, the control unit 22 includes a cooling fan drive control unit 22A, a rotation speed / air volume conversion unit 22B, an air volume integration unit 22C, an air volume integration value comparison unit 22D, and a cooling fan drive determination unit 22E. These detailed functions will be described later.

  The control unit 22 receives detection values from various sensors mounted on the vehicle. As an example of a sensor that is highly relevant to the battery pack cooling system according to the present embodiment, detection values are received from a battery pack temperature sensor 44, an intake air temperature sensor 46, a position sensor 42, and a vehicle speed sensor 48.

  The battery pack temperature sensor 44 is attached to, for example, the surface of the battery pack 10. A plurality of temperature sensors may be attached to the surface of the battery pack 10 to determine the temperature distribution. In this case, variable control of the cooling fan 18 described later may be performed based on the average of the detected temperatures of the plurality of temperature sensors, or the cooling fan 18 may be controlled based on the highest temperature among the detected temperatures of the plurality of temperature sensors. Variable control may be performed. The battery temperature T_Bat detected by the battery pack temperature sensor 44 is transmitted to the cooling fan drive control unit 22A and the cooling fan drive determination unit 22E.

  The intake air temperature sensor 46 is provided in the intake air passage 20, and at least the temperature sensing element is disposed (exposed) in the intake air passage 20. For example, the intake air temperature sensor 46 is provided closest to the battery pack 10 in the intake air passage 20 in consideration of a temperature change and the like in the intake air passage 20. For example, an intake air temperature sensor 46 is provided at a connection port with the supply port 26 of the cover 24, which is an end of the connection duct 34. The intake air temperature T_Air detected by the intake air temperature sensor 46 is transmitted to the cooling fan drive control unit 22A and the cooling fan drive determination unit 22E.

  As will be described later, the acquisition of the intake air temperature T_Air by the cooling fan drive determination unit 22E is performed in response to the reception of the permission command of the air volume integrated value comparison unit 22D, and the permission from the start of the cooling fan drive determination flow in FIG. Until the command is received, the acquisition of the intake air temperature T_Air is reserved.

  The position sensor 42 receives the rotor position θ of the fan motor 16. By differentiating the rotor position θ, the rotation speed [rpm] of the rotor and the rotation speed [rpm] of the cooling fan 18 are obtained. As described above, for simplicity, in the following description, the rotation speed of the rotor and the rotation speed of the cooling fan 18 are assumed to be equal. The rotor position θ, which is the detection value of the position sensor 42, is transmitted to the cooling fan drive control unit 22A and the rotation speed / air volume conversion unit 22B. The vehicle speed (vehicle speed), which is the value detected by the vehicle speed sensor 48, is also transmitted to the cooling fan drive control unit 22A.

  The cooling fan drive control unit 22 </ b> A performs variable speed control on the cooling fan 18 via variable speed control on the fan motor 16. The rotation speed variable control is basically performed based on the temperature T_Bat of the battery pack 10. For example, the command rotation speed increases as the battery pack temperature T_Bat increases. Further, the command speed may be multiplied by a coefficient based on the intake air temperature T_Air. For example, the coefficient decreases as the intake air temperature T_Air decreases (the final commanded rotation speed decreases).

  Further, in the present embodiment, in the rotation speed variable control of the cooling fan 18, the maximum allowable rotation speed is limited based on the vehicle speed (vehicle speed) from the viewpoint of noise suppression. Since the intake port 30 of the intake passage is exposed to the passenger compartment, the driving noise of the cooling fan 18 tends to leak into the passenger compartment, and this driving noise may lead to occupant discomfort. Therefore, in the present embodiment, the driving noise of the cooling fan 18 is masked by the road noise generated according to the driving of the vehicle, and the discomfort of the occupant is suppressed.

  Specifically, the maximum permissible rotation speed of the cooling fan 18 is limited using a vehicle speed-maximum permissible rotation speed map as shown in FIG. In this graph, the horizontal axis represents the vehicle speed, and the vertical axis represents the maximum allowable rotation speed. The vehicle speed and the magnitude of the road noise accompanying the vehicle speed are obtained in advance by a noise test, a sensory test, or the like. Further, the loudness of the driving sound corresponding to the rotation speed of the cooling fan 18 is also obtained in advance by a noise test, a sensory test, or the like. Based on the acquired data, the maximum allowable rotation speed of the cooling fan 18 according to the vehicle speed is determined.

  In performing the rotation speed variable control of the cooling fan 18, the cooling fan drive control unit 22 </ b> A controls the cooling fan 18 according to the temperature T_Bat of the battery pack 10 within a range equal to or less than the maximum allowable rotation speed of the cooling fan determined according to the vehicle speed. Change the rotation speed. For example, the cooling fan drive control unit 22A sets the initial command rotation speed based on the temperature T_Bat of the battery pack 10. Next, the cooling fan drive control unit 22A refers to the vehicle speed-maximum allowable rotation speed map to determine the maximum allowable rotation speed corresponding to the current vehicle speed. If the initial command speed is equal to or less than the maximum allowable speed, the cooling fan drive control unit 22A generates a PWM control signal based on the initial command speed to control the fan inverter 14. On the other hand, when the initial command speed exceeds the maximum allowable speed, the cooling fan drive control unit 22A resets the maximum allowable speed at that time as the command speed, and generates a PWM control signal based on this. To control the fan inverter 14.

  Further, in the present embodiment, the cooling fan drive control unit 22A executes the rotation speed variable control from the time of starting the cooling fan 18 in the stopped state. As a result, it is possible to promptly send out the stagnated air, which will be described later, as compared with the related art that is started at the minimum rotation speed.

  In controlling the driving of the cooling fan 18, the cooling fan drive determining unit 22E determines whether the cooling fan 18 can be driven based on the battery pack temperature T_Bat and the intake air temperature T_Air. For example, when the temperature T_Air of the air (intake air) taken in from the vehicle interior is equal to or higher than the battery pack temperature T_Bat, the battery pack 10 may not be able to be cooled, or the battery pack 10 may be heated by sending the intake air. Therefore, in preparation for such a case, the cooling fan drive determination unit 22E can output a drive stop command to stop the driving of the cooling fan 18 to the cooling fan drive control unit 22A.

  In the above-described cooling fan drive determination, the intake air temperature T_Air serving as a determination reference needs to be the intake air in the vehicle compartment. For example, while the cooling fan 18 is stopped, the stagnated air in the intake passage 20 may be heated to be higher than the vehicle interior air. In such a case, the temperature of the stagnated air is taken in as the intake air temperature T_Air. This may lead to an erroneous determination of stopping the cooling fan 18. Therefore, in the present embodiment, when the cooling fan 18 is started from the stop state, the intake air temperature T_Air is detected after the stagnant air in the intake passage 20 is sent out (exhausted) in advance.

  FIG. 4 illustrates a cooling fan drive determination flow according to the present embodiment. When the battery pack temperature T_Bat exceeds a predetermined threshold temperature T_th, the cooling fan 18 is started, and this flow is executed. As an initial setting, the acquisition of the intake air temperature T_Air by the cooling fan drive determination unit 22E is in a state of being reserved. As will be described later, this reserved state is released by a permission command sent from the air volume integrated value comparison unit 22D.

  The cooling fan drive control unit 22A variably controls the rotation speed of the cooling fan 18 according to the battery pack temperature T_Bat and the vehicle speed (S10). For example, as described above, the maximum allowable rotation speed is determined according to the vehicle speed, and the instruction rotation speed is adjusted according to whether the initial instruction rotation speed obtained from the battery pack temperature T_Bat is equal to or less than the maximum allowable rotation speed. At this time, the intake air temperature T_Air may be taken and reflected in the variable control.

With the activation of the cooling fan 18, the rotor position θ is transmitted from the position sensor 42 to the rotation speed / air volume conversion unit 22B. The rotation speed / air volume conversion unit 22B determines the rotation speed [rpm] of the cooling fan 18 based on the rotor position θ. Further, the rotation speed / air volume conversion unit 22B converts the rotation speed of the cooling fan 18 into the air volume Q [cm ³ / sec] of the staying air (S12). For example, a rotation speed-air volume conversion map shown in FIG. 5 is used. In this map, the horizontal axis represents the rotation speed [rpm] of the cooling fan 18 and the vertical axis represents the airflow [cm ³ / sec] of the cooling fan 18. The correspondence between the two is obtained in advance by the specification of the cooling fan 18 or an experiment.

The air volume integrating unit 22C obtains the outgoing air volume Q [cm ³ / sec] of the cooling fan 18 from the rotation speed / air volume converting unit 22B starting from the start of the cooling fan 18 and integrates the obtained air volume (S14). For example, the air volume integrating unit 22C acquires the transmitted air volume Q from the rotation speed / air volume converting unit 22B every second. By integrating the sending air volume Q, the sending air volume Va (= 体積 Q) by the cooling fan 18 is obtained.

  The delivery air volume Va is sent to the air volume integrated value comparison unit 22D. The air volume integrated value comparison unit 22D determines whether the air volume integrated value, that is, the delivery air volume Va is equal to or greater than the volume threshold value V_th (S16). For example, the volume threshold V_th is a volume (volume) in the intake passage 20 from the intake port 30 of the intake passage 20 to the intake air temperature sensor 46.

  If the delivery air volume Va is equal to or greater than the volume threshold value V_th (typically, if the delivery air volume Va reaches the volume threshold value V_th (Va = V_th)), the air that contacts the temperature-sensitive element of the intake air temperature sensor 46 is not a vehicle. It becomes indoor air. At this time, the air volume integrated value comparison unit 22D transmits a permission command to permit the acquisition of the intake air temperature T_Air from the intake air temperature sensor 46 to the cooling fan drive determination unit 22E (S18). When the delivery air volume Va is less than the volume threshold value V_th, the process returns to step S10.

  After step S18, the cooling fan drive determination unit 22E acquires the intake air temperature T_Air. At the same time, the cooling fan drive determination unit 22E acquires the battery pack temperature T_Bat. Next, the cooling fan drive determination unit 22E determines whether the intake air temperature T_Air is equal to or higher than the battery pack temperature T_Bat (S20). If the intake air temperature T_Air is equal to or higher than the battery pack temperature T_Bat, the cooling fan drive determination unit 22E outputs a drive stop command for the cooling fan 18 to the cooling fan drive control unit 22A (S22). In response to this, the cooling fan drive control unit 22A executes a stop operation. For example, the PWM control signal to the fan inverter 14 is forcibly cut off (duty ratio is set to 0), and the driving of the switching element of the fan inverter 14 is stopped.

  When the intake air temperature T_Air is lower than the battery pack temperature T_Bat, the cooling fan drive determination unit 22E does not output a drive stop command. Thus, the rotation speed variable control for the cooling fan 18 by the cooling fan drive control unit 22A is continued (S24).

  FIG. 6 shows an example in which the cooling fan drive control according to the present embodiment is performed (curve A) and an example in which the cooling fan drive control according to the related art is performed (curve B). The horizontal axis represents time, and the vertical axis represents the rotation speed of the cooling fan 18. Times t2 and t3 both indicate the time at which the intake air temperature check was performed. As shown in this example, by performing the rotation speed variable control from the start time t1 of the cooling fan 18, the cooling fan 18 is quickly controlled as compared with the related art in which the cooling fan 18 is controlled at the minimum rotation speed at the start time. The temperature check of the vehicle interior air can be executed.

  Reference Signs List 10 battery pack, 14 fan inverter, 16 fan motor, 18 cooling fan, 20 intake passage, 22 control unit, 22A cooling fan drive control unit, 22B rotation speed / air volume conversion unit, 22C air volume integration unit, 22D air volume integration value Comparison unit, 22E cooling fan drive determination unit, 30 intake port, 32 intake duct, 34 connection duct, 35 cooling fan casing, 38 filter, 42 position sensor, 44 battery pack temperature sensor, 46 intake temperature sensor, 48 vehicle speed sensor.

Claims (1)

A cooling fan that takes in air inside the vehicle and sends it to the battery pack;
An intake air temperature sensor provided in an intake passage from the air intake of the vehicle interior to the battery pack via the cooling fan,
A cooling fan control unit that performs variable control to change the rotation speed of the cooling fan according to the temperature of the battery pack in a range equal to or less than the maximum allowable rotation speed of the cooling fan determined according to the vehicle speed;
Calculating from the start of the cooling fan, integrating the air volume of the cooling fan based on the number of rotations of the cooling fan, an air volume integrating unit for calculating the volume of air sent by the cooling fan,
When the delivered air volume is equal to or greater than the volume from the air intake to the intake temperature sensor in the intake flow path, the intake air temperature is acquired from the intake temperature sensor, and the intake temperature is determined by the battery pack. A cooling fan drive determination unit that outputs a drive stop command of the cooling fan to the cooling fan control unit when the temperature is equal to or higher than a temperature of
A vehicle-mounted battery pack cooling system, comprising: