JP6804138B2 - Battery level calculator - Google Patents

Description

The present invention relates to a battery remaining amount calculation device that calculates the remaining charge amount of a battery mounted on a vehicle.

In recent years, charge control (charge / discharge control) has been widely adopted in vehicles using an engine as a drive source. Charge control is a technology that improves fuel efficiency by suppressing power generation by the alternator and reducing the load on the engine.

In charge control, for example, when the SOC (State Of Charge), which is the ratio of the remaining charge to the charge capacity (full charge) of the battery, is within a certain charge control range, power is generated by the alternator when the vehicle is decelerated. Then, the battery is charged by the power generated by the alternator, and the power generated by the alternator is stopped otherwise, and power is supplied from the battery to an electric load such as a headlight. As a result, the load on the engine can be reduced and fuel efficiency can be improved. When the SOC of the battery is below the lower limit of the charge control range, charge control is not performed, and power generation by the alternator is performed even when the vehicle is not decelerating.

The SOC of the battery is calculated by an ECU (Electronic Control Unit) having a configuration including a CPU, a memory, and the like. A current sensor that can distinguish between the charging current flowing into the battery and the discharging current flowing out of the battery is connected to the ECU. In the ECU, the remaining charge (battery remaining amount) of the battery is calculated by integrating the charge amount to the battery and the discharge amount from the battery based on the detection signal of the current sensor, and the SOC is calculated using the remaining battery amount. It is calculated.

In addition, IDS control (idling stop control) has been adopted for vehicles using an engine as a drive source. IDS control is a technology for stopping unnecessary idling rotation of an engine and improving fuel efficiency.

In IDS control, for example, when the brake pedal is depressed by the driver's foot, the brake is activated, and the vehicle speed drops below a predetermined IDS start vehicle speed, the engine is automatically stopped (idling stop). After the engine is automatically stopped, for example, when the brake pedal is released and the brake is released, the engine is automatically restarted (IDS return).
When the engine is restarted, a voltage is applied from the battery to the starter provided with the engine, and the power of the starter is transmitted to the flywheel of the engine via the starter gear to crank the engine. Then, while the engine is cranked, the spark plug of the engine is sparked, so that the engine restarts.

JP-A-2007-318888

Since the operating power of the starter is large, when the engine is restarted, the discharge current (actual value) of the battery becomes large as shown by the alternate long and short dash line in FIG. However, since the range of the current value that can be detected by an inexpensive current sensor is narrow, the detected value of the discharge current of the battery when the engine is restarted becomes a value as shown by a solid line in FIG. As a result, the amount of discharge from the battery cannot be calculated accurately, and an error occurs in the calculated value of the remaining battery level and, by extension, the calculated value of SOC.

An object of the present invention is to provide a battery remaining amount calculation device capable of accurately calculating the battery remaining amount even in a vehicle adopting IDS control.

In order to achieve the above object, the battery remaining amount calculation device according to the present invention includes an engine, a starter for cranking the engine, a generator generated by the rotation of the engine, and a battery charged by the generated power of the generator. It is a battery remaining amount calculation device used for a vehicle equipped with the above, and depends on the storage means, the current detecting means for detecting the charging current of the battery and the discharging current of the battery, and the predetermined IDS start condition. IDS control means for stopping the engine and executing IDS control for restarting the engine by operating the starter by supplying power from the battery to the starter when a predetermined IDS return condition is satisfied during the stop. Based on the detection result of the current detecting means, the remaining charge of the battery is calculated by integrating the charge amount to the battery and the discharge amount from the battery, and the calculated remaining charge amount is stored in the storage means. It includes a calculation means and a subtraction means for subtracting a discharge amount error in consideration of the power consumption of the starter from the remaining charge stored in the storage means in response to the restart of the engine by IDS control.

According to this configuration, the current detecting means detects the charging current of the battery and the discharging current of the battery. Then, the remaining amount calculating means integrates the charge amount to the battery by the generated power of the generator and the discharge amount from the battery by supplying the operating power to the starter or the like based on the detection result of the current detecting means. Based on this integration, the remaining battery level, which is the remaining charge of the battery, is calculated. The calculated remaining battery level is stored in the storage means.

In IDS control, the engine is stopped (idling stop) when a predetermined IDS start condition is satisfied. Then, when a predetermined IDS return condition is satisfied while the engine is stopped, the starter is operated and the engine is cranked by the power of the starter. Then, while the engine is cranked, the spark plug of the engine is sparked, so that the engine is restarted.

Since the operating power of the starter is large, the discharge current of the battery becomes large when the engine is restarted. Therefore, in response to the restart of the engine by IDS control, the discharge amount error considering the power consumption of the starter is subtracted from the remaining charge stored in the storage means. As a result, it is possible to prevent an error from occurring in the remaining battery level stored in the storage means each time the engine is restarted by IDS control.

Therefore, even in a vehicle that adopts IDS control, the remaining battery level can be calculated accurately.

Since the remaining battery level is calculated accurately, the charge control can be appropriately performed based on the determination of whether or not the remaining battery level is within the charge control range. Fuel efficiency can be improved by performing charge control when the remaining battery level is within the charge control range. Further, it is possible to suppress that the charge control is performed even though the actual remaining battery level is below the charge control range. As a result, deterioration of the battery due to a decrease in the remaining battery level can be suppressed, and shortening of the battery life can be suppressed.

The storage means may store an absolute amount of electricity as the remaining amount of battery (remaining amount of charge of the battery), or may store a relative value corresponding to the absolute amount of electricity. That is, storing the remaining battery level in the storage means is equivalent to storing the SOC, which is the ratio of the remaining charge amount to the charge capacity of the battery, in the storage means.

Similarly, subtracting the discharge amount error from the remaining battery level is equivalent to subtracting the ratio of the discharge amount error to the charge capacity of the battery from the SOC.

Further, the determination of whether or not the remaining battery level is within the charge control range is equivalent to the determination of whether or not the SOC is within the charge control range for SOC.

The discharge amount error in consideration of the power consumption of the starter may be a constant value or a variable value according to the friction of the engine. In the latter case, for example, the lower the engine water temperature (the temperature of the cooling water flowing through the engine), the greater the friction of the engine and the larger the power consumption of the starter. Therefore, it is preferable to set the discharge amount error to a large value. As a result, the discharge amount error according to the magnitude of the power consumption of the starter can be subtracted from the remaining battery level stored in the storage means, so that the remaining battery level can be calculated more accurately.

According to the present invention, the remaining battery level can be calculated accurately even in a vehicle adopting IDS control.

It is a block diagram which shows the electrical structure of the main part of the vehicle which mounted the ECU which concerns on one Embodiment of this invention. It is a flowchart which shows the flow of IDS control. It is a flowchart which shows the flow of the battery remaining amount update process. It is a flowchart which shows the flow of the battery remaining amount subtraction processing. It is a figure which shows the relationship between the engine water temperature and the discharge amount error. It is a flowchart which shows the flow of charge control processing. It is a graph which shows the time change of the current value of the discharge current of a battery, and the value detected by a current sensor.

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

<Electrical configuration>
FIG. 1 is a block diagram showing an electrical configuration of a main part of a vehicle 1 on which an ECU 11 according to an embodiment of the present invention is mounted.

The vehicle 1 is an automobile whose drive source is the engine 2. Along with the engine 2, a starter 3 for cranking the engine 2 and an alternator 4 for generating electricity by the rotation of the engine 2 are provided. Further, the vehicle 1 is equipped with a battery 5. The battery 5 is, for example, a lead battery having a nominal voltage of 12 V.

When the engine 2 is started, a voltage is applied to the starter 3 from the battery 5 via the power supply line 6. A flywheel is held on the crankshaft of the engine 2. When a voltage is applied to the starter 3, the plunger of the starter 3 moves and the starter gear of the starter 3 meshes with the flywheel of the engine 2. Further, the relay provided in the starter 3 is turned on, the current supplied from the battery 5 to the starter 3 increases, a large torque is input from the starter 3 to the engine 2, and the engine 2 is cranked by the torque. To torque. The engine 2 is started by sparking the spark plug of the engine 2 while the engine 2 is cranked.

Further, the voltage of the battery 5 is applied to an electric load 7 such as a wiper motor, a headlight, an air conditioner, and an audio device mounted on the vehicle 1.

The alternator 4 includes a rotor, a stator, and an IC regulator. The rotor rotates with the rotation of the crankshaft of the engine 2. The rotor is provided with a field coil (rotor coil). When the field current (excitation current) is supplied from the IC regulator to the field coil of the rotating rotor, a three-phase alternating current due to electromagnetic induction flows through the stator coil provided in the stator. The three-phase alternating current is rectified to a direct current voltage by a rectifier. The alternator 4 outputs DC power as generated power, and the generated power is supplied to the battery 5 via the power supply line 6 to charge the battery 5.

Further, the vehicle 1 is provided with, for example, a plurality of ECUs (Electronic Control Units). The plurality of ECUs include the ECU 11 described below. Each ECU has a similar hardware configuration, and is connected so as to enable bidirectional communication by a CAN (Controller Area Network) communication protocol.

The ECU 11 is provided with a CPU 12 and a memory 13 (ROM, RAM, etc.). The ECU 11 is connected to a current sensor 14 provided in relation to the negative terminal of the battery 5 and an engine water temperature sensor 15 that detects the temperature of the cooling water flowing through the engine 2 (engine water temperature). As the current sensor 14, a current sensor 14 that can distinguish and detect the charging current flowing into the negative terminal of the battery 5 and the discharging current flowing out from the negative terminal of the battery 5 is adopted. Further, although not shown, the ECU 11 has an accelerator sensor that outputs a detection signal according to the operation amount of the accelerator pedal, and an engine rotation speed sensor that outputs a pulse signal synchronized with the rotation of the crank shaft of the engine 2 as a detection signal. , Various sensors such as a throttle opening sensor that outputs a detection signal according to the opening degree (throttle opening degree) of the electronic throttle valve of the engine 2 are connected.

The ECU 11 uses the electronic throttle valve of the engine 2 to start, stop, and adjust the output of the engine 2 based on the information acquired from the detection signals of various sensors and / or various information input from other ECUs. It controls the injector, spark plug, starter 3, and so on. Further, the ECU 11 calculates the remaining battery level, which is the remaining charge of the battery 5, and controls the power generation by the alternator 4 based on the remaining battery level. Further, when the remaining battery level is calculated by the ECU 11, the calculated remaining battery level is updated and stored in the memory 13.

<IDS control>
FIG. 2 is a flowchart showing the flow of IDS control.

IDS control (idling stop control) is adopted for the vehicle 1.

In the IDS control, when the brake pedal is operated (depressed) while the vehicle 1 is traveling, the ECU 11 determines whether or not a predetermined IDS start condition is satisfied (step S1). The IDS start condition is, for example, a condition that the vehicle speed is equal to or less than a predetermined idling stop implementation vehicle speed (for example, 10 km / h), and the brake pedal is operated for a certain period of time or longer. While the brake pedal is being operated, it is determined at regular intervals whether or not the IDS start condition is satisfied.

When the IDS start condition is satisfied (YES in step S1), the engine 2 is stopped (idling stop) by the ECU 11 (step S2).

After the start of idling stop, the ECU 11 determines whether or not the predetermined IDS return condition is satisfied (step S3). The IDS return condition is, for example, a condition that the operation of the brake pedal is released during the idling stop (the driver's foot is released from the brake pedal). During the idling stop, it is determined at regular intervals whether or not the IDS start condition is satisfied.

When the IDS return condition is satisfied (YES in step S3), the starter 3 is operated by the ECU 11. The operation of the starter 3 causes the engine 2 to be cranked. Then, when the spark plug of the engine 2 is sparked during the cranking of the engine 2, the engine 2 is restarted (step S4), and the IDS control is terminated.

It should be noted that an ECU different from the ECU 11, for example, an IDS ECU for IDS control may determine whether or not the IDS start condition is satisfied. In this case, depending particular IDS start condition is met, the engine stop request is sent to the ECU 11 from IDSECU, receiving the engine stop request, the ECU 11, the engine 2 is stopped. In addition, the IDSECU determines whether or not the IDS return condition is satisfied. Then, when the IDS return condition is satisfied, the IDSECU sends an engine restart request to the ECU 11, and in response to the engine restart request, the ECU 11 restarts the engine 2.

<Battery level update process>
FIG. 3 is a flowchart showing the flow of the battery remaining amount update process.

While the ignition key switch of the vehicle 1 is on (IG on), the ECU 11 executes the battery remaining amount update process at regular intervals.

In the battery remaining amount update process, first, the current value of the charge current flowing into the battery 5 or the discharge current flowing out of the battery 5 is acquired based on the detection signal of the current sensor 14 (step S11).

Next, from the acquired current value of the charge current or the discharge current, the amount of electricity (charge amount) flowing into the battery 5 or the amount of electricity (discharge amount) flowing out of the battery 5 in one cycle of the battery remaining amount update process is calculated. (Step S12).

The previously calculated remaining battery level is stored in the memory 13. After calculating the charge amount or discharge amount, the charge amount is added to or the discharge amount is subtracted from the battery remaining amount stored in the memory 13, so that the battery remaining amount is updated and the updated battery remaining amount becomes. It is overwritten and stored in the memory 13 (step S13).

When the charge amount is represented by a positive value and the discharge amount is represented by a negative value, the charge amount or the discharge amount is newly added to the remaining battery level previously stored in the memory 13. Battery level is calculated.

<Battery level subtraction process>
FIG. 4 is a flowchart showing the flow of the battery remaining amount subtraction process. FIG. 5 is a diagram showing the relationship between the engine water temperature and the discharge amount error.

Since the operating power of the starter 3 is large, the discharge current of the battery 5 becomes large when the engine 2 is restarted by IDS control. However, when the range of the current value that can be detected by the current sensor 14 is narrow, the amount of discharge from the battery 5 cannot be calculated accurately, and the calculated value of the remaining battery level in the battery remaining amount update process is incorrect. Occurs.

Therefore, the ECU 11 determines whether or not the engine 2 has returned from the idling stop, that is, whether or not the engine 2 has been restarted by IDS control (step S21).

Then, at the time of returning from the idling stop (YES in step S21), the engine water temperature is acquired from the detection signal of the engine water temperature sensor 15 by the ECU 11. In the memory 13 of the ECU 11, the relationship between the engine water temperature [° C.] and the discharge amount error [As] shown in FIG. 5 is stored in the form of a map. The lower the engine water temperature, the larger the friction of the engine 2 and the larger the power consumption of the starter 3, so that the discharge amount error is set to a large value. When the engine water temperature is acquired by the ECU 11, the discharge amount error corresponding to the acquired engine water temperature is read from the memory 13. Then, the discharge amount error is subtracted from the remaining battery level stored in the memory 13, and the subtracted value is stored in the memory 13 as the remaining battery level by overwriting (step S22).

<Charge control>
FIG. 6 is a flowchart showing the flow of the charge control process.

Charge control is adopted in the vehicle 1. While the ignition key switch of the vehicle 1 is on, the ECU 11 executes a charge control process for charge control.

In the charge control process, the SOC (State Of Charge), which is the ratio of the remaining battery level stored in the memory 13 to the charge capacity (full charge amount) of the battery 5, is calculated.

Then, it is determined whether or not the SOC is equal to or higher than the upper limit value of the predetermined charge control range (step S31).

When the SOC is equal to or greater than the upper limit of the charge control range (YES in step S31), the power generation by the alternator 4 is stopped (step S32).

When the SOC is less than the upper limit value of the charge control range (NO in step S31), it is determined whether or not the SOC is less than the lower limit value of the charge control range (step S33).

When the SOC is not less than the lower limit of the charge control range, in other words, when the SOC is equal to or more than the lower limit of the charge control range and less than the upper limit, that is, when the SOC is within the charge control range (NO in step S33). , It is determined whether or not the vehicle 1 is decelerating (step S34).

When the vehicle 1 is not decelerating (NO in step S34), the power generation by the alternator 4 is stopped (step S35). Therefore, when the ignition key switch is turned on and the engine 2 is started, if the SOC calculated from the remaining battery level stored in the memory 13 is within the charge control range, the alternator 4 generates electric power. Instead, the battery 5 supplies the operating power to the starter 3.

When the SOC is less than the lower limit of the charge control range (YES in step S33), or when the SOC is within the charge control range and the vehicle 1 is decelerating (YES in step S34), the alternator 4 generates power. Then, the battery 5 is charged by the generated power of the alternator 4.

<Effect>
As described above, in the battery remaining amount update process shown in FIG. 3, the amount of charge to the battery 5 by the generated power of the alternator 4 and the amount of discharge from the battery 5 by the supply of the operating power to the electric load 7 and the like are performed by the ECU 11. And are integrated. Based on this integration, the remaining battery level, which is the remaining charge of the battery 5, is calculated. The calculated remaining battery level is stored in the memory 13 of the ECU 11.

In the IDS control, the engine 2 is stopped (idling stop) when a predetermined IDS start condition is satisfied. Then, when a predetermined IDS return condition is satisfied during the idling stop, the starter 3 is operated and the engine 2 is cranked by the power of the starter 3. Then, while the engine 2 is cranked, the spark plug of the engine 2 is sparked, so that the engine 2 is restarted.

Since the operating power of the starter 3 is large, the discharge current of the battery 5 becomes large when the engine 2 is restarted by IDS control. Therefore, the battery remaining amount subtraction process shown in FIG. 4 is executed, and the discharge amount in consideration of the power consumption of the starter 3 from the remaining charge stored in the memory 13 in response to the restart of the engine 2 by the IDS control. The error is subtracted. As a result, it is possible to prevent an error from occurring in the remaining battery level stored in the memory 13 each time the engine 2 is restarted (returned from idling stop) by IDS control.

Further, the lower the engine water temperature, the larger the friction of the engine 2 and the larger the power consumption of the starter 3, so that the discharge amount error is set to a large value. As a result, the discharge amount error according to the magnitude of the power consumption of the starter 3 can be subtracted from the remaining battery level stored in the memory 13, so that the remaining battery level can be calculated more accurately.

Therefore, even in a vehicle that adopts IDS control, the remaining battery level can be calculated accurately.

Since the remaining battery level is calculated accurately, the charge control can be appropriately performed based on the determination of whether or not the remaining battery level is within the charge control range. Fuel efficiency can be improved by performing charge control when the remaining battery level is within the charge control range. Further, it is possible to suppress that the charge control is performed even though the actual remaining battery level is below the charge control range. As a result, deterioration of the battery 5 due to a decrease in the remaining battery level can be suppressed, and shortening of the life of the battery 5 can be suppressed.

<Modification example>
Although one embodiment of the present invention has been described above, the present invention can also be implemented in other embodiments.

For example, in the above-described embodiment, the remaining battery level is stored in the memory 13, but the SOC may be stored in the memory 13. In this case, in the battery remaining amount subtraction process, the ratio of the discharge amount error to the charge capacity of the battery 5 may be subtracted from the SOC instead of subtracting the discharge amount error from the battery remaining amount.

Further, in the charge control process, the charge control range is set in the unit of electric energy [As], and the remaining battery charge is charged instead of determining whether or not the SOC is equal to or higher than the upper limit value of the charge control range. Whether or not it is equal to or greater than the upper limit of the control range is determined, and instead of determining whether or not the SOC is less than the lower limit of the charge control range, whether or not the remaining battery level is less than the lower limit of the charge control range. May be determined.

The discharge amount error is set to a value according to the engine water temperature, but it may be a preset constant value.

Further, the discharge amount error may be set to a value according to the engine water temperature and the outside air temperature. In this case, as shown by the two-point chain line in FIG. 5, the discharge amount error is set to a larger value as the engine water temperature is lower, and is set to a larger value as the outside air temperature is lower. It is preferable to be done.

In addition, various design changes can be made to the above-mentioned configuration within the scope of the matters described in the claims.

1 Vehicle 2 Engine 3 Starter 4 Alternator (generator)
5 Battery 11 ECU (battery remaining amount calculation device, IDS control means, remaining amount calculation means, subtraction means)
13 Memory (storage means)
14 Current sensor (current detection means)

Claims (1)

A battery remaining amount calculation device used in a vehicle equipped with an engine, a starter for cranking the engine, a generator generated by the rotation of the engine, and a battery charged by the power generated by the generator.
Memories and
A current detecting means for detecting the charging current of the battery and the discharging current of the battery, and
When the predetermined IDS start condition is satisfied, the engine is stopped, and when the predetermined IDS return condition is satisfied during the stop, the starter is started by supplying electric power from the battery to the starter. An IDS control means that executes IDS control to operate and restart the engine, and
Based on the detection result of the current detecting means, the remaining charge of the battery is calculated by integrating the charge amount to the battery and the discharge amount from the battery, and the calculated remaining charge amount is stored in the storage means. Remaining amount calculation means to make
A subtraction means for subtracting a discharge amount error in consideration of the power consumption of the starter from the remaining charge stored in the storage means in response to the restart of the engine by the IDS control.
Including an engine water temperature sensor that detects the engine water temperature of the engine.
Said subtracting means, said in due IDS control of restarting of the engine, the discharge amount and the engine coolant temperature was set to a large value the discharge amount error the lower the engine water temperature detected by the engine coolant temperature sensor The relationship with the error is moved so that the discharge amount error is set to a larger value as the outside temperature is lower, and the discharge amount error is set according to the engine water temperature and the outside temperature from the relationship. Calculator.

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