JPH0583998A - Ac generator for vehicle - Google Patents

Abstract

PURPOSE:To provide an AC generator for vehicle in which self-excited rising rotational speed is lowered at the time of starting. CONSTITUTION:The AC generator 1 for vehicle comprising an exciting coil 5 mounted on a rotor for generating a rotating magnetic field and a stator coil 3 applied on a stator is provided with a first voltage establishing circuit 11 for detecting the voltage of the stator coil 3 and feeding a current to the exciting coil 5 and a second voltage establishing circuit 16 for controlling the current of the exciting coil 5 by means of a battery 2 power supply, wherein the voltages can be established at low rotational speed by operating both first and second voltage establishing circuits 11, 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle AC generator capable of rapidly establishing a voltage even at a low rotation speed.

[0002]

2 and 3 show a concrete example of a circuit for establishing excitation of a conventional vehicle alternator. In FIG. 2, 1 is a generator, 2 is a battery, 3 is a stator coil, 4 is a rectifier of the voltage generated in the stator coil 3, supplies exciting power to the exciting coil 5, and supplies electric power to charge the battery 2. Rectifying diode circuit for supplying, 5 is an exciting coil for generating a voltage in the generator, 6 is an ignition switch, 7 is an indicator lamp, 8 is a bypass resistor,
Reference numeral 9 is a voltage establishing circuit. In FIG. 2 described above, when the vehicle alternator is started, electric power for initial excitation is obtained from the battery 2 via the bypass resistor 8 connected in parallel to the ignition switch 6 and the display lamp 7. .. However, since the combined resistance of the bypass resistor 8 and the display lamp 7 is several tens of Ω, a large voltage drop may occur in this circuit, and the exciting coil 5 may not be supplied with sufficient power. Therefore, in order to secure a sufficient magnetomotive force at the time of starting the generator, it is necessary to rotate the engine of the vehicle at a high speed.

FIG. 3 shows another circuit for establishing the excitation of a conventional vehicle alternator. In FIG. 3, the voltage establishing circuit 9 is provided in parallel with the display lamp 7. Therefore, as shown in the circuit of FIG. 2, the electric power for exciting the exciting coil 5 does not pass through the display lamp 7 and the bypass resistor 8 but directly from the battery 2 to the exciting coil 5 via the voltage establishing circuit 9. As shown in FIG.
The problem of the voltage drop between the conventional indicator lamp 7 and the bypass resistor 8 shown in FIG. 1 is solved for the time being, and the voltage of the generator 1 itself can be established at a low rotation speed. In FIG. 3, 1
Reference numeral 0 is a charge lamp display control circuit which detects the voltage of the generator 1 and operates. It is to be noted that, in FIG. 3, reference numerals not described have the same configurations as the same reference numerals in FIG. The charge lamp display control circuit 10 described above operates when the ignition switch 6 is turned on and then a voltage comes from the neutral point (A) of the generator 1 to turn on the display lamp 7 and turn on the voltage establishing circuit 9. to start.

[0004]

However, in the circuit shown in FIG. 3, a large exciting current continues to be supplied to the voltage establishing circuit 9 while the ignition switch 6 is closed, so that the ignition switch 6 remains closed. If the engine is not started, the battery 2 will be consumed quickly. Further, in FIG. 3, the charge lamp display control circuit 10 detects the voltage at the neutral point (A) of the generator as a display for displaying the charge which is unavoidable in the vehicle and uses this voltage.
It is necessary to draw this control line from the neutral point (A) of the winding of the generator because the charge state is displayed on the display lamp 7 by controlling the However, the cost of the control circuit is increased. SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, and it is an object of the present invention to provide a vehicle AC generator that further reduces the self-excited startup rotation speed in the initial stage of starting the generator.

[0005]

The vehicle alternator of the present invention includes an exciting coil provided on a rotor for generating a rotating magnetic field, a stator coil wound around the stator, and A diode bridge circuit for rectifying the AC output of the stator coil, a voltage adjusting device for supplying electric power from the stator coil to the exciting coil, a lamp display circuit for displaying a charging status, and a control circuit for the lamp display circuit. In a vehicle alternator having, a detection circuit for detecting a voltage of a stator coil, a series circuit of a diode switching circuit for supplying a current to an exciting coil controlled by the detection circuit, and a diode, and a lamp, A first voltage establishing circuit connected in parallel with the display circuit;
A second voltage establishing circuit that controls the current of the exciting coil by controlling the main transistor, and operates the first voltage establishing circuit and the second voltage establishing circuit to reduce the voltage at a low rotation speed. Is established.

[0006]

According to the present invention, when the exciting current is supplied to the exciting coil through the lamp display circuit when the engine is stopped, the rotor is stopped, so that no voltage is generated in the stator coil of the generator. .. When the engine is started and the rotor rotates, a small exciting current flows through the exciting coil of the rotor through the lamp display circuit that displays the charge state, and a rotating magnetic field is generated around the stator coil, which causes the rotor to rotate AC induced electromotive force is generated in the child coil. Then, the detection circuit of the first voltage establishing circuit that detects the voltage generated in the stator coil controls the transistor switching circuit, and supplies the exciting current to the exciting coil via the diode connected in the forward direction. As described above, when the current is supplied from the first voltage establishing circuit to the exciting coil, the first voltage is higher than the voltage applied to the exciting coil from the lamp display circuit.
Since the voltage applied from the voltage establishing circuit to the exciting coil becomes high, no current flows from the lamp display circuit to the exciting coil, and the display lamp of the lamp display circuit is turned off.

Further, when a current having a flow rate larger than that of the exciting current supplied from the lamp display circuit is supplied from the first voltage establishing circuit to the exciting coil, the stator coil of the generator is further increased. The first voltage establishing circuit increases the exciting current supplied to the exciting coil based on the induced electromotive force and the increase in the voltage of the stator coil. Then, when the voltage generated in the stator coil becomes higher than the voltage applied to the exciting coil by the first voltage establishing circuit, no current is supplied to the exciting coil by the first voltage establishing circuit. On the other hand, as the current is no longer supplied to the exciting coil from the first voltage establishing circuit, the generated voltage of the stator coil of the generator is applied to the exciting coil by the voltage adjusting device, and the generator power is generated. Since the exciting current based on the voltage is supplied to the exciting coil,
Self-excitation by the generator itself is established. Immediately after the generator starts rotating as described above, when the generated voltage of the generator synergistically increases and the exciting current supplied to the exciting coil reaches a certain amount, the second voltage establishing circuit operates. Based on this, the main transistor is controlled so that the generated voltage has a constant value.

[0008]

1 is a block diagram of a vehicle AC generator showing an embodiment of the present invention. In FIG. 1, a first voltage establishing circuit 11 is connected in parallel with the indicator lamp circuit 7 between the positive side of the battery 2 and one end of the exciting coil 5. The first voltage establishing circuit 11 is composed of a transistor switching circuit 12, a diode 13 and a voltage control transistor 14. The transistor switching circuit 12 is controlled by the voltage control transistor 14. The transistor switching circuit 12 may be Darlington connection. Then, the second voltage establishing circuit 16 is connected to the DC circuit of the ignition switch 6, the bypass resistor 8 and the backflow prevention diode 15 described above. On the other hand, the stator coil 3 of the generator is star-connected, and each output terminal is connected to the rectifying diode circuit 4 for DC output, and is connected to the exciting coil 5 through the auxiliary diode 17.

An exciting coil 5 for generating a voltage by a rotating magnetic field is wound around a rotating magnetic pole. The rotating magnetic pole is rotated by the power of the vehicle engine by a rotating shaft or pulley (not shown). The positive side of the rectifying diode circuit 4 is directly connected to the battery 2, and the negative side of the rectifying diode circuit 4 is connected to the negative side of the battery 2 directly or via a chassis. The ignition switch 6 is connected to the exciting coil 5 in series with the lamp display circuit 7 and the backflow prevention diode 15 which are connected in parallel with the bypass resistor 8.

The operation of the generator circuit described above will be described below. In the above-mentioned configuration, by turning on the ignition switch 6 when the engine is stopped,
When an exciting current is supplied to the exciting coil 5 of the rotor via the lamp display circuit 7, the rotor is stopped, so that no voltage is generated in the stator coil 3 of the generator 1. Therefore, only the indicator lamp for displaying the charge state of the battery 2 is turned on, and the generator 1 does not generate power. Further, when a small exciting current flows through the exciting coil 5 of the rotor via the lamp display circuit 7 at the time of starting the engine, a rotating magnetic field is generated around the stator coil 3 and an AC induced electromotive force is generated in the stator coil 3. Occurs. Then, the voltage of the stator coil 3 is applied to the base of the voltage control transistor 14, so that the voltage control transistor 14 is turned on. Further, as the voltage control transistor 14 is turned on, a base current flows through the transistor switching circuit 12, so that the transistor switching circuit 12 is also turned on, and the exciting coil 5 is turned on via the diode 13 connected in the forward direction. The exciting current will be supplied to. Here, since the voltage applied to the exciting coil from the transistor switching circuit 12 is higher than the voltage applied to the exciting coil 5 from the battery 2 via the load such as the lamp display circuit 7, the flow direction of the current is reduced. The display lamp of the lamp display circuit 7 is turned off even if the ignition switch 6 is closed.

Further, when a current whose flow rate is larger than the exciting current supplied from the lamp display circuit 7 is supplied from the transistor switching circuit 12 of the first voltage establishing circuit 11 to the exciting coil 5, the generator is generated. Higher induced electromotive force is generated in the stator coil 3 of No. 1, and the voltage of the stator coil 3 is increased. Then, when the voltage applied to the emitter and the base of the transistor switching circuit 12 via the rectifying diode circuit 4 becomes higher than the voltage applied from the battery 2, the transistor switching circuit 12 and the diode in the first voltage establishing circuit 11 Since the voltage drop when reaching the exciting coil 5 via the auxiliary diode 17 is lower than the voltage drop when going to the exciting coil 5 via 13, the stator coils 3 via the auxiliary diodes 17 ... As a result, a voltage is applied to the exciting coil 5. Here, as the output voltage from the generator 1 becomes higher than the output voltage from the transistor switching circuit 12, the transistor switching circuit 1
2 collector current stops flowing. After this, the forward current between the emitter and the base of the transistor switching circuit 12 continues to flow, but since the exciting current is no longer supplied from the transistor switching circuit 12 to the exciting coil 5, the first voltage establishing circuit 11 The operation effectively stops. The diode 13 is for preventing current from flowing from the auxiliary diode 17 to the battery 2 through the transistor switching circuit 12. Thus, when the generated voltage of each stator coil 3 of the generator 1 is applied to the exciting coil 5 via the auxiliary diode 17, the exciting current based on the generated voltage of the generator 1 is supplied to the exciting coil 5. When the self-excitation is established and the power generation voltage of the generator 1 increases synergistically, the excitation coil 5
The exciting current supplied to the device will increase dramatically, and it will be possible to obtain a sufficient generated voltage to supply the external load.

As described above, when the engine is started, an exciting current is supplied to the rotor having a low rotational speed through the lamp display circuit 7 to generate an electromotive force in the stator 3 at a low voltage. First voltage establishing circuit 1 using low voltage
By supplying an exciting current having a larger flow rate from 1 to the exciting coil 5, the output of the generator 1 can be efficiently increased when the engine is running at low speed. Therefore, in the generator 1 according to the present invention, the self-excited rising speed in the initial stage of starting the generator is improved to a low range, and the generator can be rapidly started up. In addition, in FIG.
The backflow prevention diode 15 connected in series with the lamp display circuit 7 is connected to the lamp display circuit 7 via the auxiliary diode 17 from the generator 1 when the generator 1 establishes self-excitation.
This is to prevent the lamp from lighting due to the current flowing back to the side.

In order to keep the generated voltage that synergistically increases due to self-excitation constant, the second voltage establishing circuit 16 has a transistor 19 connected between the base of the main transistor 18 and the ground. And a Zener diode 20 connected to the base of the transistor 19 so that a current can be supplied by the Zener effect. The operation of the Zener diode 20 will be described below. For example, when the voltage applied to the battery 2 reaches a certain value or more, the Zener diode 20 is passed through an appropriate load resistance and rectifying means.
Zener breakdown occurs due to the reverse voltage applied to
When a current flows through the base of the transistor 19, the transistor 19 is turned on. By doing so, a voltage higher than the operating voltage is not applied to the base of the main transistor 18, so that the main transistor 18 is turned off and the exciting current to the exciting coil 5 is stopped. Then, when the generated voltage of the generator 1 drops due to the supply of the exciting current, the reverse voltage applied to the Zener diode 20 drops below the Zener voltage, and the transistor 19 is turned off.
The main transistor 18 is turned on again. In this way, the second voltage establishing circuit 16 performs on / off control of the main transistor 18, whereby the power generation voltage of the generator 1 can be held substantially constant. The second voltage establishing circuit 16 used in this embodiment is a known circuit that turns on and off the exciting current supplied to the exciting coil 5. The above-mentioned constant voltage can be adjusted by a variable resistor connected to the cathode side of the Zener diode 20.

Generally, the electromotive force of the generator is proportional to the number of revolutions up to the limit region if the generated magnetic flux is constant. Therefore, by providing a circuit for increasing the initial magnetic flux as described above, the initial magnetic flux amount increases at a lower rotational speed,
The voltage will be established at a low speed. The present inventor was able to reduce the number of revolutions at the time of voltage establishment to about 80 rpm with a generator having an output voltage of 12 V and a total output of about 3 KW, compared with a conventional generator.

[0015]

In summary, according to the present invention, the exciting coil provided in the rotor for generating the rotating magnetic field, the stator coil wound around the stator, and the AC output of the stator coil are rectified. In the vehicle alternator, the diode bridge circuit, the voltage adjusting device for supplying electric power from the stator coil to the exciting coil, the lamp display circuit for displaying a charging status, and the control circuit for the lamp display circuit are provided. A detection circuit for detecting the voltage of the stator coil, and a series circuit of a diode switching circuit for supplying a current to the excitation coil which is controlled by the detection circuit and a diode, and which is connected in parallel to the lamp display circuit. 1 voltage establishing circuit and a second voltage establishing circuit for controlling the current of the exciting coil by controlling the main transistor Since the voltage is established at a low rotational speed by operating the first voltage establishing circuit and the second voltage establishing circuit, the rotational speed at the time of establishing the voltage of the self-excited generator is reduced. Therefore, the pulley ratio of the generator can be reduced correspondingly, and there is an effect that the life of the bearings and brushes during high-speed operation can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a vehicle AC generator according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an example of a configuration of a conventional vehicle alternator.

FIG. 3 is a block diagram showing another example of the configuration of a conventional vehicle AC generator.

[Explanation of symbols]

 1 Generator 2 Battery 3 Stator Coil 4 Generator Coil 5 Excitation Coil 6 Ignition Switch 7 Lamp Display Circuit 8 Bypass Circuit 9 Voltage Establishing Circuit 10 Charge Lamp Display Control Circuit 11 First Voltage Establishing Circuit 12 Transistor Switching Circuit 13 Diode 14 Voltage control transistor 15 Backflow prevention diode 16 Second voltage establishment circuit 17 Auxiliary diode 18 Main transistor 19 Transistor 20 Zener diode

Claims (1)

[Claims] 1. An exciting coil provided in a rotor for generating a rotating magnetic field, a stator coil wound around the stator, and a diode bridge circuit for rectifying an alternating current output of the stator coil. A vehicular AC generator having a voltage adjusting device for supplying electric power from the stator coil to the exciting coil, a lamp display circuit for displaying a charging status, and a control circuit for the lamp display circuit, wherein: A first voltage establishing circuit having a detection circuit for detecting a voltage and a series circuit of a diode and a transistor switching circuit controlled by the detection circuit for supplying a current to an exciting coil and connected in parallel to the lamp display circuit. And a second voltage establishing circuit for controlling the current of the exciting coil by controlling the main transistor, the first voltage establishing circuit A vehicle alternator characterized in that a voltage is established at a low rotational speed by operating a path and a second voltage establishing circuit.