JP4029683B2 - Vehicle power generation control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle power generation control device.
[0002]
[Prior art]
From the standpoint of improving fuel efficiency and preventing catalyst heating, so-called fail cut may be performed to stop or limit the fuel supply to the engine during vehicle deceleration.
[0003]
For example, Japanese Patent No. 2760037 discloses a technique for stopping or limiting power generation of a charging generator for a certain period of time after detecting a signal that fuel supply has been resumed after fuel cut has been completed.
[0004]
[Problems to be solved by the invention]
However, as disclosed in Japanese Patent No. 2760037, when the power generation of the charging generator is stopped or restricted for a certain period of time, the battery is in a discharged state. Therefore, depending on the degree of deterioration of the battery, the deterioration of the battery is accelerated rapidly. There is a problem that an effective power generation time limit cannot be set according to the vehicle situation.
[0005]
[Means for Solving the Problems]
Therefore, the vehicle power generation control device of the present invention includes an alternator driven by an engine to generate power, fuel supply control means for stopping or limiting fuel supply to the engine under predetermined conditions, and the engine by the fuel supply control means. stopped or limitation of the fuel supply stops power generation by once the alternator is canceled to have an alternator control means for increasing gradually until the power generation voltage of the alternator reaches the predetermined value immediately after the, the .
[0006]
【The invention's effect】
According to the present invention, it is possible to suppress overshoot and undershoot of the engine speed after the fuel supply to the engine is restarted while minimizing the promotion of battery deterioration due to battery discharge.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
[0008]
FIG. 1 is an explanatory diagram schematically showing a system configuration of a vehicle power generation control device according to the present invention.
[0009]
The engine 1 is provided with a crank pulley 3 that rotates integrally with the crankshaft 2. A belt 6 is wound around the crank pulley 3 and an alternator pulley 5 attached to the rotating shaft of the alternator 4. That is, the alternator 4 and the crankshaft 2 are configured to rotate synchronously.
[0010]
The alternator 4 controls the power generation amount according to a command from an ECM (engine control module) 8 that monitors the voltage of the on-vehicle battery 7, and whether the generated power is charged in the battery 7. , Supplied to an electric load (LOAD) of a vehicle such as a headlamp. When no power is generated by the alternator 4, electric power is supplied to the above-described electric load of the vehicle by discharging from the battery 7.
[0011]
The ECM 8 receives signals from a vehicle speed sensor 9 that detects the vehicle speed and an engine speed sensor 10 that detects the speed of the engine 1. Further, the ECM 8 controls the operation of the engine 1 based on the fuel injection command value determined according to the driving state of the vehicle so that the optimum fuel injection is performed according to the driving state of the vehicle.
[0012]
The ECM 8 performs so-called fail cut control for stopping or limiting the fuel supply to the engine 1 to a very small amount when the vehicle is decelerated from a state where the engine speed is equal to or higher than a predetermined speed.
[0013]
Further, the ECM 8 performs power generation by the alternator 4 during the fail cut, and after the fail cut is finished, the fuel supply to the engine 1 is resumed and at the same time, the power generation by the alternator 4 is once stopped. The alternator 4 is controlled so as to gradually increase the generated voltage until it reaches a predetermined value.
[0014]
Here, the flow of power generation control of the alternator 4 performed in the ECM 8 will be described with reference to the flowchart of FIG.
[0015]
In step 11, the operation of the engine 1 is controlled based on the fuel injection command value that is stored in advance in the ECM 8 and is determined according to the driving state of the vehicle.
[0016]
In step 12, it is determined whether or not the fuel is currently being cut. If the fuel is being cut, the process proceeds to step 13 to read the engine speed.
[0017]
In step 14, it is determined whether or not the engine speed read in step 13 is equal to or less than the fuel supply restart speed. If it is equal to or less than the fuel supply restart speed, the fuel cut is stopped and the fuel injection is restarted. At the same time, the process proceeds to step 15. The fuel supply restarting rotational speed is a rotational speed that is larger than the idle rotational speed by a predetermined rotational speed.
[0018]
In step 15, power generation in the alternator 4 is temporarily stopped.
[0019]
In step 16, the rate of increase α of the generated voltage of the alternator 4 is determined according to the vehicle deceleration rate (vehicle speed change rate) β during fuel cut.
[0020]
In step 17, the power generation voltage of the alternator 4 is gradually increased at the increase rate α determined in step 16 until it reaches a predetermined value.
[0021]
FIG. 3 is a timing chart showing the behavior of the vehicle speed, the engine speed, the fuel injection amount, and the power generation voltage of the alternator 4 during deceleration.
[0022]
If the accelerator pedal is released when the engine speed is greater than or equal to a predetermined value (timing A in FIG. 3), the vehicle starts to decelerate and the engine 1 stops fuel injection (fuel cut). Note that the power generation voltage of the alternator 4 during the fuel cut is increased by a predetermined amount compared to the power generation voltage at the normal time before the fuel cut.
[0023]
When the engine speed gradually decreases and reaches a predetermined value close to the idle speed, fuel injection is resumed by a command from the ECM 8 (timing B in FIG. 3) and power generation by the alternator 4 is temporarily stopped. Then, the ECM 8 temporarily stops the power generation of the alternator 4 and then changes in vehicle speed β during vehicle deceleration until the power generation voltage of the alternator 4 reaches a predetermined value (the inclination of the vehicle speed between A and B in FIG. 3). The generated voltage is gradually increased at an increase rate α corresponding to. That is, when the change rate of the vehicle speed is β1, the increase rate of the generated voltage is α1, when the change rate of the vehicle speed is β2, the increase rate of the generated voltage is α2, and when the change rate of the vehicle speed is β3. The increase rate of the generated voltage is α3. More specifically, when the change rate β of the vehicle speed is large (the inclination is large), the increase rate α of the generated voltage of the alternator 4 is small (the inclination is small).
[0024]
In this way, while the fuel supply to the engine 1 is stopped or restricted, power is generated by the alternator 4 and at the same time the stop or restriction of the fuel supply to the engine 1 is released, power generation by the alternator 4 is once performed. Since the power generation voltage of the alternator 4 is gradually increased until reaching a predetermined value after that, the engine speed after fuel cut is less than the idle speed while minimizing the deterioration of the battery 7 due to battery discharge. Overshooting or undershooting can be suppressed.
[0025]
Further, since the increase rate α of the power generation voltage of the alternator 4 that once stopped power generation after the fuel cut is determined according to the deceleration rate β when the vehicle decelerates, the rotational fluctuation of the engine speed is minimized, and Control can be performed so that the fuel injection amount after fuel cut is minimized.
[0026]
In the first embodiment described above, the rate of change of the vehicle speed when the vehicle is decelerated is used as the rate of deceleration β. However, the rate of change of the engine speed when the vehicle is decelerated, the deceleration signal from the ABS, the brake pedal stroke The deceleration rate β may be calculated using a signal or the like.
[0027]
Next, reference examples of the present invention will be described. In this reference example , in the power generation control device for a vehicle having the system configuration shown in FIG. 1 described above, while the fuel supply to the engine 1 is stopped or restricted (during fuel cut), power is generated by the alternator 4 and the engine The power generation by the alternator 4 is restricted at the same time as the stop or restriction of the fuel supply to 1 is released, and the power generation restriction by the alternator 4 is released when the battery voltage (VB) falls below a predetermined value R set in advance. It is controlled by ECM8.
[0028]
FIG. 4 is a timing chart relating to power generation control of the alternator 4 in this reference example . During the fuel cut, power is generated by the alternator 4. Therefore, the power generated by the alternator 4 is supplied to the electric load (LOAD) of the vehicle, and the electric power of the vehicle is supplied from the battery 7. No power is supplied to the load, and the battery voltage VB does not decrease.
[0029]
Then, after the fuel cut is completed, the fuel supply to the engine 1 is resumed, and at the same time, the power generation by the alternator 4 is restricted. Here, the ECM 8 controls the power generation voltage of the alternator 4 in order to control the amount of power generated by the alternator 4, and the limitation of power generation by the alternator 4 makes the power generation voltage of the alternator 4 a predetermined low power generation voltage. Is achieved.
[0030]
When the power generation in the alternator 4 is restricted, electric power (LOAD) of the vehicle is supplied with electric power from the battery 7, and the battery voltage decreases as time passes. And the restriction | limiting of the electric power generation by the alternator 4 is cancelled | released at the timing when the battery voltage (VB) became below the predetermined value R set beforehand.
[0031]
Then, after the battery voltage reaches the predetermined value R and the limit of power generation is released by the alternator 4, the power generation voltage of the alternator 4 is gradually increased. Note that the rate of increase in the generated voltage of the alternator 4 is determined according to the deceleration rate of the vehicle during fuel cut, as in the first embodiment.
[0032]
FIG. 5 is a flowchart showing a control flow of the vehicle power generation control device in this reference example .
[0033]
When the engine speed is reduced to the fuel supply restarting speed due to the deceleration of the vehicle during the fuel cut, the limit of power generation of the alternator 4 is started (step 21), and the power generation voltage at the alternator 4 is a predetermined low power generation. The command value is output from the ECM to the alternator 4 so as to be a voltage (step 22). In other words, since the alternator 4 is controlled so that the generated voltage becomes a predetermined low generated voltage, power is supplied from the battery 7 to the electric load of the vehicle, and the battery voltage gradually decreases. To go.
[0034]
Then, when it is determined in step 23 that the battery voltage (VB) has become equal to or less than the predetermined value R, the process proceeds to step 25, and the power generation restriction of the alternator 4 is released. That is, the power generation voltage at the alternator 4 is gradually increased from the low power generation voltage described above to supply the electric power generated by the alternator 4 to the electric load of the vehicle and at the same time the power generated by the alternator 4 to the battery 7 is generated. The supplied electric power is supplied and the battery 7 is charged.
[0035]
If it is determined in step 23 that the battery voltage (VB) is not less than or equal to the predetermined value R, the process proceeds to step 24.
[0036]
In step 24, it is determined whether or not there is a power generation amount change command of the alternator 4 due to an increase in the electrical load of the vehicle. In other words, when the alternator 4 is controlled at a predetermined low power generation voltage, if the electric load of the vehicle increases due to lighting of the headlight or the like, the process proceeds to step 25 and the power generation limitation at the alternator 4 is released.
[0037]
In such a reference example, it is possible to reliably prevent the battery 7 from being overdischarged by monitoring the battery voltage.
[0038]
Further, when the engine is running at a low speed, the power generation load of the alternator relatively increases as the engine load, and the influence of the power generation amount of the alternator on the stability of rotation control and the fuel consumption of the engine increases. Therefore, in order to limit the amount of power generated by the alternator before and after the fuel re-injection timing after the fuel cut to improve control stability and reduce fuel consumption, it is desirable to continue the power generation limit of the alternator for a long time. If the amount of power generated by the alternator is limited, it will not be possible to sufficiently supply electricity to the electric load of the vehicle, and the insufficient amount will be taken out of the battery. If this situation continues for a long time, the charge amount of the battery decreases, and there is a possibility that the next engine start may be impossible. Therefore, when the alternator power generation is limited, the battery voltage is monitored.
[0039]
In other words, the power generation by the alternator 4 is restricted at the same time when the fuel supply to the engine 1 is stopped or restricted, and the power generation restriction by the alternator 4 is released when the battery voltage drops below a predetermined reference value R. Since the power generation of the alternator 4 can be restricted until immediately before the battery 7 is overdischarged, the fuel consumption of the engine 1 caused by the power generation drive of the alternator 4 can be suppressed, and the fuel consumption of the engine 1 can be efficiently reduced. it can.
[0040]
In the reference example described above, when the fuel is re-injected from the fuel cut state, the power generation of the alternator 4 is limited so that the power generation voltage of the alternator 4 becomes a predetermined low power generation voltage. When the fuel is re-injected from this state, the power generation of the alternator 4 may be controlled so that the power generation voltage of the alternator 4 becomes zero.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram schematically showing a system configuration of a vehicle power generation control device according to the present invention.
FIG. 2 is a flowchart showing a flow of alternator power generation control in the first embodiment of the present invention.
FIG. 3 is a timing chart according to the first embodiment of the present invention.
FIG. 4 is a timing chart in a reference example of the present invention.
FIG. 5 is a flowchart showing a flow of alternator power generation control in a reference example of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Engine 4 ... Alternator 7 ... Battery 8 ... ECM (fuel supply control means, alternator control means)

Claims (2)

An alternator that is driven by an engine to generate electricity;
Fuel supply control means for stopping or limiting fuel supply to the engine under predetermined conditions;
While the fuel supply to the engine is stopped or restricted by the fuel supply control means, the alternator generates power and the fuel supply control means releases or stops the fuel supply to the engine. And an alternator control means for once stopping the power generation by the alternator and gradually increasing the power generation voltage of the alternator until reaching a predetermined value immediately thereafter . The fuel supply control means stops or restricts fuel supply to the engine during deceleration of the vehicle,
The power generation voltage increase rate when the power generation voltage of the alternator is gradually increased from a state in which power generation by the alternator is stopped to reach a predetermined value is variably controlled according to the deceleration rate during vehicle deceleration. The vehicle power generation control device according to claim 1.

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