JPH06284597A - Alternator controller - Google Patents

Abstract

PURPOSE:To provide an alternator controller which can eliminate probability of engine stop while limiting fuel consumption. CONSTITUTION:An AC power generated by an alternator 11 is converted into a DC power with a rectifying diode 12 and is then stored in a battery to supply the power to an electric load 15 through a switch 14. A terminal voltage of the battery is monitored with an IC regulator 16, and a duty ratio signal DR for controlling a field coil current output from an F terminal 161 of the regulator is input to a controller 17. When the terminal voltage is higher than the predetermined threshold value voltage, the field coil current is controlled by an allowable maximum duty ratio determined as a function of the number of revolutions as a duty ratio which goes not give any fluctuation on the number of revolutions in place of DR.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alternator control device mounted on an automobile, and more particularly to an alternator control device capable of suppressing the occurrence of engine stop.

[0002]

2. Description of the Related Art In automobiles, electric power is supplied from a battery although a defogger and other electric loads are used. Then, the AC power generated by the alternator driven by the engine is converted into DC power by the thyristor and charged in the battery. The amount of power generated by the alternator is controlled by controlling the field current.

FIG. 4 is a power generation characteristic diagram of the alternator, in which the horizontal axis represents the engine speed Ne and the vertical axis represents the load with respect to the speed, that is, the power generation amount Wa of the alternator. The parameter is the field current. That is, in a normal use state in which the engine speed Ne is equal to or higher than the predetermined speed Nn, if the amount of power generated by the alternator Wa is increased when the battery voltage Vb decreases to a predetermined threshold voltage or lower, The number Ne decreases, which may cause so-called engine stop.

In order to solve this problem, when increasing the power generation amount Wa by the alternator, it is common to perform so-called idle-up in which the engine speed Ne is increased by a predetermined amount.

[0005]

However, if the engine speed Ne is increased, it is unavoidable that the fuel efficiency is deteriorated. Furthermore, if the increase in engine speed by a predetermined amount is insufficient, the risk of engine stop cannot be completely avoided.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an alternator control device capable of suppressing deterioration of fuel consumption and avoiding the risk of engine stop.

[0007]

SUMMARY OF THE INVENTION An alternator control device according to the present invention provides an alternator driven by an engine, a battery for storing output power of the alternator, and an alternator output voltage to a predetermined target voltage. The regulator that adjusts the duty ratio of the alternator field current, the maximum allowable duty ratio that is determined as a function of the engine speed, the regulator duty ratio that is output from the regulator, the battery terminal voltage, and the predetermined threshold voltage. And the regulator duty ratio is higher and the battery terminal voltage is higher, the duty ratio control adjusts the alternator field current by the allowable maximum duty ratio instead of the regulator duty ratio. It is composed of parts.

[0008]

In the alternator control device according to the present invention, when the battery terminal voltage is not abnormally lowered, the engine duty does not change greatly instead of the regulator duty ratio determined by the regulator. The power generation amount of the alternator is controlled by the maximum allowable duty ratio that gives the maximum allowable power generation amount.

[0009]

1 is a block diagram of an embodiment of an alternator control device according to the present invention, in which a rotor coil 111 of an alternator 11 is rotationally driven by an engine to generate AC power. Then, this AC power is converted into DC by the bridge-connected rectifying diode 12 and stored in the battery 13.

The battery 13 supplies electric power via the switch 14 to an electric load 15 which is, for example, a defogger.
The terminal voltage of the battery 13 is monitored by the IC regulator 16, and the IC regulator 16 controls the battery 1
The duty ratio signal is output from the F terminal 161 of the IC regulator 16 so that the terminal voltage of 3 becomes a predetermined voltage.

The duty ratio signal output from the F terminal 161 of the IC regulator 16 is once sent to the electronic control unit 1.
Input to 7. The electronic control unit 17 is connected to the field coil 112 of the alternator 11 and controls the output voltage of the alternator 11 by controlling the current flowing through the field coil 112.

FIG. 2 is a flowchart of a duty ratio control routine executed by the electronic control unit 17, which is interrupted at regular time intervals. In step 20, the engine speed Ne, the terminal voltage BATT of the battery 13, and the regulator duty ratio DR output from the F terminal of the regulator 16 are read.

In step 21, the maximum allowable duty ratio DRmax is obtained as a function of the engine speed Ne. FIG. 3 is a graph for determining the maximum allowable duty ratio DRmax, where the horizontal axis represents the engine speed Ne and the vertical axis represents the maximum allowable duty ratio DRmax. The maximum allowable duty ratio DRmax is preset as a duty ratio that does not cause fluctuations in the engine speed in a normal idling state.

In step 22, the terminal voltage B of the battery 13
It is determined whether ATT is higher than a predetermined threshold voltage VTH. If an affirmative decision is made in step 22, the routine proceeds to step 23, where the output duty ratio DOUT is set to the allowable maximum duty ratio DRmax and the routine proceeds to step 26.
When a negative determination is made in step 22, the output duty ratio DOUT is set to the regulator duty ratio DR in step 24, and then the process proceeds to step 25, where the target idling engine speed Nd of the engine is increased by a predetermined amount ΔN, that is, the idling. After performing the up, proceed to step 26.

In step 26, the engine speed Ne
Is lower than the target rotation speed Nd. When a positive determination is made in step 26, the idle-up is performed again in step 27, then the output duty ratio DOUT is set to the allowable maximum duty ratio DRmax in step 28, and the process proceeds to step 29.

If a negative determination is made in step 26, it is determined that further idle-up is unnecessary and the process directly proceeds to step 29. At step 29, the output duty ratio DOU
The current flowing through the field coil of the alternator is controlled based on T, and this routine is ended.

[0017]

According to the alternator control device of the present invention, when the battery terminal voltage does not drop abnormally, the engine duty does not change greatly instead of the regulator duty ratio determined by the regulator. By controlling the power generation amount of the alternator by the maximum allowable duty ratio that gives the maximum allowable power generation, it is possible to improve fuel efficiency and reduce the risk of engine stop.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment.

FIG. 2 is a flowchart of a duty ratio control routine.

FIG. 3 is a graph for determining an allowable maximum duty ratio.

FIG. 4 is a power generation characteristic diagram of the alternator.

[Explanation of symbols]

 11 ... Alternator 12 ... Rectifier diode 13 ... Battery 14 ... Switch 15 ... Electric load 16 ... IC regulator 17 ... Electronic control unit

Claims (1)

[Claims] 1. An engine, an alternator driven by the engine, a battery that stores output power of the alternator, and a duty of a field current of the alternator so that an output voltage of the alternator becomes a predetermined target voltage. In an alternator control device including a regulator that adjusts a ratio, a maximum allowable duty ratio determined as a function of engine speed and a regulator duty ratio output from the regulator, and a terminal voltage of the battery, When the regulator duty ratio is higher and the battery terminal voltage is higher than the predetermined threshold voltage, the field of the alternator is replaced by the maximum allowable duty ratio instead of the regulator duty ratio. Equipped with a duty ratio controller that adjusts the current Alternator control device according to claim and.