JP3797242B2 - Vehicle power generation control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power generation control device for a vehicle including an engine (internal combustion engine), a generator, and a battery.
[0002]
[Prior art]
In conventional vehicle power generation control, when the engine decelerates the fuel cut, the generator's power generation voltage is increased to forcibly charge the battery to improve fuel efficiency by recovering power, and after the fuel supply is resumed, the power generation voltage is decreased for a predetermined time. There is one in which the engine load is reduced by suppressing no power generation to suppress a rapid decrease in engine rotation (see JP-A-2-276499).
[0003]
[Problems to be solved by the invention]
However, in the above prior art, since the time during which no power is generated is constant, the amount of discharge during this period becomes too large, and the battery charge amount is insufficient (SOC <100%). In some cases, sulfation (crystallization of discharge products) occurs in the battery and the charging performance is lowered. If the non-power generation time is shortened, the engine rotation cannot be sufficiently prevented from decreasing.
[0004]
The present invention has been made paying attention to such conventional problems, and it is an object of the present invention to provide a vehicle power generation control device capable of preventing a decrease in battery performance while satisfying an improvement in fuel consumption and prevention of a decrease in engine rotation. And
[0005]
[Means for Solving the Problems]
For this reason, the invention according to claim 1
When the engine decelerates the fuel, the generator voltage is increased and the battery is forcibly charged.After the forcible charging is completed, the generator voltage is reduced for a predetermined time according to the amount of charge during the forcible charging, and no power is generated. It is characterized by doing.
[0006]
According to the invention of claim 1,
The battery can be discharged at the time of no power generation according to the amount of electric power collected by forced charging, and it is possible to prevent deterioration in performance due to a decrease in the state of charge of the battery while satisfying fuel efficiency improvement and prevention of engine rotation reduction.
The invention according to claim 2
The predetermined time is a time for discharging from the battery by the amount of charge during forced charging.
[0007]
According to the invention of claim 2,
The amount of discharge during no power generation can be exactly matched with the amount of charge during forced charging, and high-precision control can be performed.
The invention according to claim 3
The charge amount during the forced charge is calculated as an integrated value of the charge current.
[0008]
According to the invention of claim 3,
The amount of charge during forced charging can be calculated accurately.
The invention according to claim 4
The predetermined time is a time corresponding to a forced charging time.
The predetermined time for no power generation can be set without calculating the charge amount or providing a current sensor therefor, and can be controlled easily and at low cost.
[0009]
The invention according to claim 5
Forcible charging is resumed when a deceleration fuel cut state occurs while the generator is not generating power.
According to the invention of claim 5,
When a deceleration operation is performed during a discharge with no power generation at the time of resuming fuel supply and the fuel is cut again, the power can be recovered without waste by restarting forced charging.
[0010]
The invention according to claim 6
After the restarted forced charge, the time generator according to the balance between the charge amount at the previous forced charge and the discharge amount at the time of no power generation is set to no power generation.
After the forced charging is resumed during the non-power generation, the non-power generation time when the fuel is supplied again can be appropriately controlled according to the charge / discharge balance so far.
[0011]
The invention according to claim 7
When the battery charge amount after the end of forced charging is below a predetermined level, the generator is prohibited from generating no power.
According to the invention of claim 7,
If the amount of battery charge is insufficient even after forcible charging, it is possible to avoid insufficient charging by prohibiting the generator from generating no power and suppressing discharge.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a system configuration of a vehicle power generation control device according to an embodiment of the present invention.
An alternator (generator) 2 driven by the engine 1 and a battery 3 for charging electric power generated by the alternator 2 are provided, and an electric load 4 of the vehicle is connected to the alternator 2 and the battery 3. A current sensor 5 for detecting the charge / discharge current of the battery 2 is connected.
[0013]
The engine 1 includes a throttle valve 11 for controlling the amount of intake air and a fuel injection valve 12, and a rotation speed sensor 13 for detecting the engine rotation speed and a throttle sensor 14 for detecting the opening of the throttle valve 11 are arranged. It is installed.
Signals from the various sensors are input to the control unit 21. The control unit 21 receives fuel from the fuel injection valve 12 when the throttle valve 11 is in a fully closed idle state and the engine speed is decelerated more than a predetermined value. The fuel cut control for stopping the injection is performed, and then the recovery control for restarting the fuel injection when the engine speed becomes the recovery value or less is performed.
[0014]
Further, in order to maintain the charge amount of the battery 3 at an appropriate amount, the normal control for controlling the power generation voltage of the alternator 2 to a set voltage (for example, 14V) is performed, while the fuel cut control and the recovery control are performed in the present invention. The generated voltage of the alternator 2 is controlled so as to perform such forced charging and no power generation control.
The power generation control of the alternator according to the first embodiment of the present invention will be described according to the flowchart of FIG.
[0015]
In step 1, it is determined whether the fuel cut control is being performed. If the fuel cut control is being performed, the process proceeds to step 2.
In step 2, the power generation voltage of the alternator 2 is increased to a voltage sufficiently higher than the battery voltage (for example, 15.5 V), and the battery 3 is forcibly charged.
In step 3, the charge amount at the time of the forced charge is integrated. Specifically, the charging current vCHAI [A / h] detected by the current sensor 5 is converted into a charging current value vCHAI / 360000 per sampling time [10 ms] and integrated to obtain an integration as follows: A charge amount vCHADD is calculated.
[0016]
vCHADD = vCHADDz + vCHAI / 360000
However, vCHADDz determines whether or not the fuel cut control has ended in the previous value step 4 of vCHADD, and returns to step 3 and repeats the integration of the charge amount before the end.
When it is determined in step 4 that the fuel cut control is finished, the process proceeds to step 5 to determine whether or not the battery charge state SOC (state of charge) is equal to or greater than a predetermined amount set to about 70 to 80%. Specifically, the battery charge state SOC is calculated as follows. When the relay that connects the battery 3 and the power supply circuit is OFF when the vehicle is stopped for a long time, the initial value of the state of charge SOC is obtained based on the initial value of the battery open-end voltage, and then the charge detected by the current sensor 5 is detected. The current state of charge SOC is calculated while integrating the discharge current as + during charging and as-during discharging.
[0017]
If it is determined in step 5 that the battery state of charge SOC is greater than or equal to a predetermined value, and it is determined that the battery state of charge SOC is insufficient to affect the electrical load control even if non-power generation control is performed, the process proceeds to step 6.
In step 6, no power generation control is started by lowering the generated voltage of the alternator 2 to a value sufficiently smaller than the battery voltage, for example, about 11V.
[0018]
In step 7, the current charge amount vCHADD of the battery is calculated by subtracting the discharge amount during the non-power generation control. Specifically, by subtracting the discharge current value vCHAI / 360000 per sampling time [10 ms] from the accumulated charge amount vCHADD during the forced charge, the battery charge amount vCHADD is calculated as in the following equation.
[0019]
vCHADD = vCHADDz-vCHAI / 360000
In step 8, it is determined whether or not the battery charge amount vCHADD calculated in step 7 is 0 or less, and when it is 0 or less, that is, it is determined that the charged part at the time of forced charging is almost discharged. Sometimes, the process proceeds to step 9 where the non-power generation control is terminated and the power generation voltage of the alternator 2 is set to a voltage during normal control, for example, about 14.4V.
[0020]
Further, during the no-power generation control before the charge amount vCHADD of the battery becomes 0 or less, it is determined in step 10 whether or not the deceleration operation is performed again to enter the fuel cut state. If not, the process returns to step 7 as it is. The calculation of the charge amount vCHADD is repeated, but if the fuel cut state is entered, the process returns to step 2. As a result, forced charging is performed again, and in step 3, the charging current value vCHAI / 360,000 is added to the current charging amount vCHADD of the battery to calculate the integrated charging amount vCHADD. Thereafter, when the fuel cut is finished and no power generation control is performed, the discharge current value vCHAI / 360,000 is subtracted from the integrated charge amount vCHADD, so that the charge amount during forced charging and the discharge amount during no power generation are balanced. The charged amount vCHADD is calculated.
[0021]
Further, when it is determined in step 4 that the battery state of charge SOC is less than the predetermined value and the non-power generation control is performed, the battery state of charge SOC is insufficient and may affect the electric load control. Without performing power generation control, the process proceeds to step 9 and immediately switches to normal control.
FIG. 3 shows power generation control of the alternator according to the second embodiment of the present invention. The second embodiment controls the discharge time during no power generation according to the charge time during forced charge. The difference from the first embodiment is that the charge time vTIME during forced charge is set in step 3 ′. Accumulate as in the equation,
vTIME = vTIMEz + 1
In step 7 ′, the discharge time (unit time multiplied by gain) is subtracted to calculate the accumulated time vTIME as in the following equation:
vTIME = vTIMEz−1 (× gain)
In step 8 ′, it is determined whether the accumulated time vTIME is 0 or less.
[0022]
This method eliminates the need for detection of the charge / discharge current, and does not require a current sensor, and can be implemented at low cost.
FIG. 4 is a diagram illustrating a state during power generation control of the alternator.
[Brief description of the drawings]
FIG. 1 is a diagram showing a system configuration of a vehicle power generation control device according to an embodiment of the present invention.
FIG. 2 is a flowchart showing power generation control of the alternator according to the first embodiment.
FIG. 3 is a flowchart showing power generation control of an alternator according to a second embodiment.
FIG. 4 is a time chart showing a state during the power generation control.
[Explanation of symbols]
1 Engine 2 Alternator 3 Battery 5 Current sensor 12 Fuel injection valve 13 Rotational speed sensor 14 Throttle sensor 21 Control unit

Claims (7)

When the engine decelerates the fuel, the generator voltage is increased and the battery is forcibly charged.After the forcible charging is completed, the generator voltage is reduced for a predetermined time according to the amount of charge during the forcible charging, and no power is generated. A power generation control device for a vehicle. The vehicle power generation control device according to claim 1, wherein the predetermined time is a time for discharging from the battery by a charge amount during forced charging. The power generation control device for a vehicle according to claim 2, wherein the amount of charge during the forced charging is calculated as an integrated value of charging current. The vehicle power generation control device according to claim 1, wherein the predetermined time is a time corresponding to a forced charging time. The power generation control device for a vehicle according to any one of claims 1 to 4, wherein forced charging is restarted when a deceleration fuel cut state is entered while the generator is not generating power. The time generator according to the balance between the charge amount at the time of forced charge and the discharge amount at the time of no power generation after the restarted forced charge is ended, and the generator is set to no power generation. The vehicle power generation control device according to any one of 5. The vehicle power generation device according to any one of claims 1 to 6, wherein when the amount of battery charge after the end of forced charging is equal to or lower than a predetermined level, no power generation by the generator is prohibited.

Images