JP2010091496A - Electronic control unit for vehicle, economy running system, battery residual capacity calculating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic control unit for a vehicle, an economy running system, and a battery residual capacity calculating method for calculating battery residual capacity with high accuracy, without using a current sensor. <P>SOLUTION: The electronic control unit 12 for the vehicle calculates the battery residual capacity of a battery 21 in which electric power is charged by rotation of an engine, and includes a charging current map 34 in which the charging current fluctuating with the charging time is registered, correspondingly to the battery temperature and the battery voltage during engine start-up, a charge amount calculating means 33 which calculates the charge amount by accumulating the charging current by reading the charging current from the charging current map 34 based on the detected battery temperature and the battery voltage during engine start-up, a discharge amount calculating means 32 which calculates the discharge amount of an auxiliary machine during engine stop, and a battery residual capacity calculating means 35 which calculates the battery residual capacity from the charge amount and the discharge amount. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicular electronic control unit, an eco-run system, and a battery remaining amount calculation method for calculating a remaining battery level of a battery mounted on a vehicle, and more particularly to a vehicular electronic control unit that calculates a remaining battery level without using a current sensor. The present invention relates to an eco-run system and a battery remaining amount calculation method.

  Economy running and automatic idling stop (hereinafter simply referred to as “eco-run system”) are known in which an internal combustion engine (hereinafter referred to as “engine”) is automatically stopped when the vehicle stops. When the vehicle speed becomes zero, such as when the vehicle is waiting for a signal, the engine is automatically stopped, so that fuel consumption can be reduced to improve fuel consumption and CO2 emissions. In the eco-run system, the engine is automatically stopped when predetermined automatic stop conditions are satisfied, for example, whether or not the accelerator pedal is depressed, the remaining battery level, whether or not the brake pedal is depressed, and the coolant temperature.

  The remaining battery level is included in the condition in order to prevent the battery from running out while the engine is stopped. Conventionally, the remaining battery level is calculated from the charging current and discharging current detected by the current sensor. However, current sensors and associated circuits are said to be relatively expensive. For this reason, the eco-run system which does not use an electric current sensor is considered (for example, refer patent documents 1 and 2). Patent Document 1 preliminarily stores data related to the average current consumption and discharge characteristics of various loads mounted on the vehicle, and estimates the discharge current from the load usage state to detect the battery charge amount. Is disclosed.

  However, since the charge state detection method described in Patent Document 1 does not consider the power generation amount, the remaining battery level becomes inaccurate when the generator generates power.

In Patent Document 2, the amount of discharge is calculated from the load usage state and the power consumption, the amount of charge is calculated from the engine speed and the charging time, and the remaining amount of the battery is calculated by estimating the charge / discharge balance of the battery. A charge state detection method is disclosed.
Japanese Patent Laid-Open No. 2001-4724 JP 2003-18754 A

  As described in Patent Document 2, the power generation amount may be affected by the product of the engine speed and the charging time, but the actual charge amount is affected by temperature and battery voltage, so the power generation amount is charged as it is. It does not always match the quantity. Therefore, if the amount of power generation is simply calculated as in the charging state detection method described in Patent Document 2, the remaining battery level may be inaccurate.

  In view of the above problems, an object of the present invention is to provide a vehicle electronic control unit, an eco-run system, and a battery remaining amount calculation method that accurately calculate a remaining battery amount without using a current sensor.

  In view of the above problems, the present invention is an electronic control unit for a vehicle that calculates a remaining battery level of a battery that is charged with the rotation of an engine, and charging is performed in association with a battery temperature and a battery voltage at the time of engine start. A charging current map in which charging currents that vary with time are registered, and the charging current is read from the charging current map based on the detected battery temperature and the battery voltage at the time of engine start, and the charging current is integrated to calculate the charging amount. A charge amount calculating means for calculating, a discharge amount calculating means for calculating a discharge amount of an auxiliary machine when the engine is stopped, and a battery remaining amount calculating means for calculating a battery remaining amount from the charge amount and the discharge amount. Features.

  It is possible to provide a vehicle electronic control unit, an eco-run system, and a battery remaining amount calculation method that accurately calculate the remaining battery amount without using a current sensor.

The best mode for carrying out the present invention will be described below with reference to the drawings.
The charging current of the battery is generally larger as the temperature is higher and larger as the battery voltage is lower. Therefore, even if the charging time is the same, the amount of charge changes depending on the temperature and the battery voltage. Further, when the battery voltage changes due to charging, the charging current also changes, so the charging current changes with time. In the present embodiment, it is possible to accurately calculate the remaining battery level by determining the charging current in advance according to such factors that affect the charging current.

  FIG. 1 shows an example of the battery charge acceptance current map 34. The vertical axis represents the charging current to the battery, and the horizontal axis represents the elapsed time from the previous start (hereinafter referred to as the charging time). In addition, although two curves are shown in the figure, one shows the charging current when the battery voltage at the engine start is small and the battery temperature is high, and the other shows the battery voltage at the engine start is high. And the charging current when the battery temperature is low ”is shown. In secondary batteries using chemical changes, such as lead-acid batteries and lithium ion batteries, the higher the temperature, the faster the chemical change rate, so the higher the temperature, the faster the chemical change and the larger the charging current. In general, in a lead-acid battery, the lower the battery voltage, the smaller the remaining amount of the battery. Therefore, the lower the battery voltage, the higher the acceptability of the charging current and the larger the charging current. Therefore, as shown in the figure, the charging current can be determined according to the battery temperature and the battery voltage at the time of starting the engine.

  Further, in FIG. 1, the charging current decreases with the charging time in any curve. This represents that the acceptability of the charging current decreases with charging. Such a downward trend of the curve with respect to the charging time is considered to be substantially the same for the same battery 21 depending on the temperature and the battery voltage at the time of engine start.

  Therefore, the battery charge acceptance current map 34 is registered in advance as shown in FIG. 1, and the charge current is determined with reference to the map, whereby the charge amount can be calculated with high accuracy. The battery charge acceptance current map 34 is digitized at intervals of 0.1 volts, 0.1 degrees, 1 second, for example, according to the relationship between the battery voltage at the start of the engine, the battery temperature, and the charging time. If so, charging currents other than the two curves shown can be acquired.

  Note that the relationship between the battery voltage and the magnitude of the charging current also varies depending on the nature of the secondary battery and the design of the charging method, so the charging current may increase as the battery voltage increases. However, once the magnitude of the charging current with respect to the battery voltage and the battery temperature is determined, the battery charging acceptance current map 34 as shown in FIG.

  FIG. 2 shows an example of a schematic configuration diagram of the eco-run system 100 of the present embodiment. The eco-run system 100 is controlled by an eco-run ECU (Electronic Control Unit) 12. The eco-run ECU 12 includes an engine ECU 11, a battery 21, a voltage sensor 18, a temperature sensor 19, a blower (blower) 17, a headlamp 16, a wiper 15, power generation. The machine 14 and the motor 13 are connected. The blower 17, the headlamp 16, and the wiper 15 (hereinafter referred to as “auxiliary machine 22” when not distinguished from each other) are examples of the auxiliary machine 22 that consumes power. Is also included. Note that the vehicle of the present embodiment only needs to include at least an internal combustion engine such as a gasoline engine or a diesel engine that can generate power, and may be a hybrid vehicle or an electric vehicle shown in the drawing.

  The eco-run ECU 12 and the engine ECU 11 have a computer including a CPU, a RAM, a ROM, a nonvolatile memory, an ASIC (Application Specific Integrated Circuit), and the like. The eco-run ECU 12 transmits to the engine ECU 11 an eco-run permission signal for permitting eco-run and an eco-run prohibition signal for prohibiting eco-run based on conditions described later. In a state where the eco-run permission signal is received, the engine ECU 11 automatically stops the engine 10 when the automatic stop condition of the engine 10 is satisfied, and restarts the engine 10 when the restart condition of the engine 10 is satisfied.

  The auxiliary machines 22 such as the wiper 15, the headlamp 16, and the blower 17 can be driven by any of the electric power supplied from the battery 21 and the generator 14. The battery 21 is a secondary battery such as a nickel metal hydride battery, a lithium ion battery, or a lead storage battery, and is connected to the generator 14 via an inverter (not shown). The battery 21 may include a plurality of low voltage (for example, 12V) and high voltage (for example, 36 to 42V). By providing the high voltage battery 21, the high load auxiliary machine 22 such as an air conditioner can be used without restarting the engine 10 while the engine is stopped.

  Moreover, although it was set as the structure which generate | occur | produces with the generator 14 integral with the motor 13 in FIG. 2, you may provide the alternator other than the generator 14, and you may provide only the alternator. The power generation by the alternator is a known one that transmits the rotation of the engine 10 by an endless belt.

  The engine 10 and the motor 13 are directly connected via a clutch that connects and disconnects the rotation output, and the vehicle is driven only by the engine 10, only the motor 13, or both the engine 10 and the motor 13. The motor 13 and the generator 14 have a regeneration mode and a power running mode. In the regeneration mode, the rotational output from the engine 10 or the driving force transmitted from the drive shaft during deceleration is converted into electric power, and the battery 21 is charged. , And supplied to the auxiliary machine 22 in use. Note that the rotational output of the engine 10 may be transmitted to some of the auxiliary machines 22 via an endless belt.

  Further, in the power running mode, power for driving the drive shaft is generated by receiving power supply from the battery 21 with the clutch connected. The regenerative mode or power running mode is switched based on the state of charge of the battery 21 (SOC (State of Charge), hereinafter referred to as the battery remaining amount), the operation amount of the accelerator pedal, the vehicle speed, and the like.

  The eco-run ECU 12 switches the power operation mode and the regenerative mode, switches the clutch on / off, controls the amount of power generated by the motor 13, and controls the remaining battery level. The engine ECU 11 detects the engine speed, the air flow, the accelerator pedal operation amount, the detected value of the exhaust gas sensor, etc., and performs known engine control for controlling the fuel injection amount, ignition timing control, air-fuel ratio, and the like. In order to determine the automatic stop condition and the restart condition, the engine ECU 11 includes vehicle speed information detected by the vehicle speed sensor, a detection signal from the brake pedal stroke sensor or master cylinder pressure sensor, and an accelerator opening detected by the accelerator opening sensor. Information, water temperature information detected by the water temperature sensor, and the like are input.

  The charging control of the eco-run ECU 12 will be described. In the operating state of the engine 10, the eco-run ECU 12 connects the clutch, rotates the motor 13 by the rotational force of the engine 10, and causes the generator 14 to generate power. The eco-run ECU 12 estimates the remaining battery capacity by a method to be described later, calculates the required power generation amount according to the remaining battery power, adjusts the power generation amount of the motor 13 and the generator 14 according to the required power generation capacity, Charge. The eco-run ECU 12 sets an upper limit value for the generated current so that the motor 13 is not heated. The inverter provided in the battery 21 rectifies the generated alternating current, converts the voltage, and charges the battery 21. The power generation method is such that when the motor 13 is rotated by the supplied current, electric power is generated from the generator 14 according to the current and the rotation speed of the motor 13.

  When the engine 10 is stopped, the clutch connecting the engine 10 and the motor 13 is disengaged, and power is supplied from the battery 21 to the auxiliary machine 22 according to the use state of the auxiliary machine 22, and the motor 13 is turned on if necessary. Some auxiliary machines 22 are driven.

  The automatic stop condition and the restart condition will be described. The conditions for automatic stop of the eco-run system 100 are, for example, a) the vehicle speed is zero, b) the brake pedal is depressed, c) the accelerator pedal is not depressed, and d) the water temperature is within a predetermined range. E) that the remaining battery level is equal to or greater than the reference charge amount, and the engine ECU 11 determines that the automatic stop condition is satisfied when all of these conditions are satisfied. In the present embodiment, an eco-run permission signal is used instead of the condition of e).

  In a state where the eco-run permission signal is received, for example, when the vehicle stops due to a signal waiting or the like, the engine ECU 11 determines whether or not an automatic stop condition is satisfied. When it is determined that the condition has been established, the eco-run ECU 12 stops the engine 10. For example, the rotation of the engine 10 is stopped by quickly stopping the fuel injection from the fuel injection valve, the ignition control of the spark plug, and the like.

  On the other hand, when the restart condition is satisfied while the engine 10 is automatically stopped, the engine ECU 11 restarts the engine 10. The restart condition is whether or not any one of the automatic stop conditions is not satisfied. If it is determined that the restart condition is satisfied, the engine ECU 11 connects the clutch and supplies power from the battery 21 to rotationally drive the motor 13 to crank the engine 10. When the engine speed reaches a predetermined value due to cranking, the engine ECU 11 performs fuel injection control and ignition timing control based on the crank position, cam position, and the like to drive the engine 10 to an operating state. The engine 10 may be started by a starter motor different from the motor 13, or the start may be supported by driving the motor 13 in the crawling mode prior to starting the engine.

[Calculation of remaining battery charge 36]
The remaining battery charge 36 can be calculated from the amount of charge to the battery 21 and the amount of discharge from the battery 21. FIG. 3 shows an example of a functional block diagram of the eco-run ECU 12. The discharge amount calculation unit 32, the charge amount calculation unit 33, the battery remaining amount calculation unit 35, and the eco-run permission determination unit 37 are implemented by a CPU of the eco-run ECU 12 or a hardware such as an ASIC. Further, the battery charge acceptance current map 34 and the power consumption table 31 are stored in advance in the non-volatile memory of the eco-run ECU 12. In addition, the charge amount calculation unit 33 stores the latest battery remaining amount 36 while updating the RAM or nonvolatile memory.

-Calculation of charge amount First, calculation of the charge amount will be described. Since the battery 21 is charged when the engine 10 is in an operating state, the charge amount calculation unit 33 starts calculating the charge amount triggered by the engine start. The engine start may be either restart from the automatic stop state or engine start manually by the occupant. When the engine start signal is received from the engine ECU 11, the eco-run ECU 12 detects the battery voltage at the time of engine start from the voltage sensor 18 and the battery temperature from the temperature sensor 19. Then, the battery charging acceptance current map 34 is referred to based on the battery voltage and the battery temperature at the time of starting the engine, and the associated charging current I _j is read out.

The amount of charge may be calculated from the integrated value of the charging current I _j , for example. Therefore, the charge amount can be calculated by the following formula. However, t _j is the cycle time [seconds] until the charging current I _j is read out. Therefore, the dimension of charge is equal to coulomb.
Charge amount = Σ {charging current I _j [A] × t _j [s]}
Since the charging current I _j changes with time, the charge amount is obtained by integrating the charging current I _j for each cycle time until the charging current I _j is read.

  The battery charge acceptance current map 34 does not need to use the same curve as the charging time elapses. This is because when charging is started, the battery temperature may rise, and the same temperature is not always maintained. Therefore, it is preferable to periodically detect the battery temperature and read the corresponding charging current from the battery charging acceptance current map 34. On the other hand, since the battery voltage reflects the remaining battery capacity 36 at the time of starting the engine, the battery voltage having the same curve is used even if the charging time elapses.

-Calculation of discharge amount Next, calculation of the discharge amount will be described. Since the battery 21 is not provided with a current sensor, the amount of discharge must also be calculated using the power consumption table 31. The power consumption table 31 is a table in which the power consumption of the auxiliary machine 22 is registered.

  FIG. 4 shows an example of the power consumption table 31. Power consumptions W1 to W9 are stored in association with each supplementary operation mode. Therefore, the discharge amount calculation unit 32 can calculate the discharge amount based on the power consumption table 31 if the auxiliary machine 22 being used is known. The usage status of each supplementary note can be acquired from the ECU that controls the accessory 22 via the in-vehicle network. The discharge amount calculation unit 32 acquires the usage status of the auxiliary machine 22 by, for example, periodically inquiring each ECU of the usage status of the auxiliary machine 22.

The calculation of the discharge amount will be described by taking as an example the case where the headlamp 16 is used at “Hi”. Since the unit of power consumption [W] = [A] × [V], the current consumption I _h [A] is obtained from the voltage consumption [V]. The consumption voltage [V] of the auxiliary machine 22 of the in-vehicle device is mostly 12 [V], and the consumption voltage (for example, 42 [V]) of the other special auxiliary machine 22 is also known. Therefore, the current consumption I _h [A] is calculated from I _h [A] = power consumption [W] / power consumption [V]. Power consumption I _h may be registered as it is in the power consumption table 31.

Even if the auxiliary machine 22 is used, when the engine 10 is in an operating state, the amount of power generated by the generator 14 is supplied directly to the auxiliary machine 22, and no electric power is discharged from the battery 21. Therefore, when the engine 10 is in an operating state, it is not necessary to calculate the amount of discharge during that time even if the auxiliary machine 22 is used. That is, the discharge is performed when the auxiliary machine 22 is used and the engine 10 is stopped. Therefore, the discharge amount is calculated from the following equation. Note that t _h is the usage time of the auxiliary machine 22 when the engine is stopped. The discharge amount calculation unit 32 performs the calculation for each auxiliary machine 22 and calculates the total as the discharge amount.
Discharge amount = I _h [A] × t _h [s]
-Calculation of the battery remaining amount 36 The battery remaining amount calculation part 35 calculates and memorize | stores the battery remaining amount 36 from charge amount and discharge amount.
Battery remaining amount 36 = original battery remaining amount + charge amount + discharge amount The original battery remaining amount is, for example, based on a value when the remaining battery amount 36 can be regarded as 100% from the battery voltage and the battery temperature. It is updated every time the charge amount or the discharge amount is calculated. Since the original remaining battery level is updated, the latest remaining battery level 36 can always be grasped. Further, the reference battery remaining amount 36 may be determined using a map for determining the battery remaining amount 36 from the battery voltage and the battery temperature.

[Battery remaining amount calculation procedure]
The battery remaining amount calculation procedure will be described with reference to the flowchart of FIG. This flowchart is repeatedly executed every predetermined cycle time.
First, the charge amount calculation unit 33 determines whether or not the engine 10 has been started (S10). The engine may be restarted by an eco-run or by a passenger manually. If the engine 10 does not start (No in S10), the process proceeds to step 60.

When the engine 10 is started (Yes in S10), the charge amount calculation unit 33 detects the battery voltage and the battery remaining amount 36 (S20). Thereby, since the battery charge acceptance current map 34 can be referred to, the charge current corresponding to the battery voltage and the battery temperature at the time of starting the engine is read (S30). The charge amount calculation unit 33 reads the charge current from the battery charge acceptance current map 34 as the charge time elapses. Then, the charge amount calculation unit 33 calculates the charge amount by integrating the charge current I _j (S40).

  Next, the discharge amount calculation unit 32 determines whether or not the engine 10 has stopped (S50). If engine 10 does not stop (No of S50), it will progress to Step S90 and battery remaining amount 36 will be updated.

  When the engine 10 is stopped (Yes in S50), the discharge amount calculation unit 32 determines whether or not the auxiliary machine 22 is in use (S60). When the auxiliary machine 22 is not in use (No in S60), it is not necessary to calculate the discharge amount, so the process proceeds to step S90 and the remaining battery capacity 36 is updated.

When the auxiliary machine 22 is in use (Yes in S60), the discharge amount calculation unit 32 reads the power consumption of all the auxiliary machines 22 used from the power consumption table 31 (S70). Then, the discharge amount is calculated from the discharge amount = current consumption I _h xx use time t _h [s] (S80).

  Next, the process proceeds to step S90, where the remaining battery level calculation unit 35 calculates the remaining battery level 36 from “original remaining battery level + charge amount + discharge amount” (S90). As described above, the remaining battery level 36 can be accurately calculated without a current sensor.

  Then, the eco-run permission determination unit 37 compares the battery remaining amount 36 with the reference charge amount (S100). If the battery remaining amount 36 is larger than the reference charge amount, the eco-run permission is permitted (S110). If it is less than the charge amount, eco-run is prohibited (S120). The engine ECU 11 can determine whether or not to automatically stop the engine 10 based on the eco-run permission signal or the eco-run prohibition signal.

(Automatic stop judgment)
The automatic stop determination procedure of the engine 10 of the eco-run system 100 will be described based on the flowchart of FIG. This flowchart is repeatedly executed every predetermined cycle time.

  The engine ECU 11 determines whether or not an automatic stop condition is satisfied (S210). This automatic stop condition does not include the remaining battery level 36. If the automatic stop condition is not satisfied (NO in S210), the process proceeds to step S240.

  When the automatic stop condition is satisfied (Yes in S210), the engine ECU 11 determines whether an eco-run permission signal is received (S220). For example, the determination is made with reference to a flag that is turned on by the eco-run permission signal and turned off by the eco-run prohibition signal. When the eco-run permission signal has not been received (NO in S220), the process proceeds to step S240.

  When the eco-run permission signal is received (Yes in S220), the engine ECU 11 stops the engine 10 (S230). Thereby, excessive fuel consumption and exhaust gas emission can be reduced.

  On the other hand, returning to Steps S210 and S220, when the automatic stop condition is not satisfied (NO in S210) and when the eco-run permission signal is not received (No in S220), the engine ECU 11 is conditioned on the condition that the engine 10 is automatically stopped. Is restarted (S230). That is, a condition for restarting the engine 10 is that the automatic stop condition is not satisfied.

  As described above, the eco-run system 100 of the present embodiment accurately calculates the remaining battery capacity 36 by storing the charging current corresponding to the charging characteristics of the battery in association with the battery temperature and the battery voltage. can do.

It is an example of a battery charge acceptance current map. It is an example of the schematic block diagram of an eco-run system. It is an example of a functional block diagram of an eco-run ECU. It is an example of a power consumption table. It is an example of the flowchart figure which shows a battery remaining charge calculation procedure. It is an example of the flowchart figure which shows the automatic stop determination procedure of the engine of an eco-run system.

Explanation of symbols

10 Engine 11 Engine ECU
12 Eco-run ECU
DESCRIPTION OF SYMBOLS 13 Motor 14 Generator 18 Voltage sensor 19 Temperature sensor 21 Battery 22 Auxiliary machine 31 Power consumption table 34 Battery charge acceptance current map 100 Eco-run system

Claims (3)

An electronic control unit for a vehicle that calculates a remaining battery level of a battery charged with electric power by rotation of an engine,
A charging current map in which charging currents that vary with charging time are registered in association with battery temperature and battery voltage at engine start,
Charge amount calculation means for reading the charge current from the charge current map based on the detected battery temperature and the battery voltage at the time of engine start, and calculating the charge amount by integrating the charge current;
A discharge amount calculating means for calculating a discharge amount of the auxiliary machine when the engine is stopped;
Battery remaining amount calculating means for calculating a remaining battery amount from the charged amount and the discharged amount;
A vehicle electronic control unit comprising: In an eco-run system that automatically stops the engine when the automatic stop condition is satisfied and restarts the engine when the restart condition is satisfied,
The automatic stop condition includes a condition that a remaining battery amount calculated by the vehicle electronic control unit according to claim 1 is larger than a reference charge amount.
Eco-run system characterized by that. A battery remaining amount calculation method for a battery that is charged with electric power by rotation of an engine,
Reading the charging current based on the detected battery temperature and the battery voltage at the time of starting the engine from a charging current map in which charging currents varying with the charging time are registered in association with the battery temperature and the battery voltage at the time of starting the engine; ,
A charge amount calculating means for calculating the charge amount by integrating the charge current; and
A step of calculating a discharge amount of the auxiliary machine when the engine is stopped;
A battery remaining amount calculating means calculating a remaining battery amount from the charge amount and the discharge amount;
A battery remaining charge calculation method characterized by comprising:

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