JP3028691B2 - Regulator with overvoltage protection circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overvoltage protection circuit provided with an overvoltage protection circuit for detecting an excessive voltage and performing a protection operation in a regulator of a generator such as an alternator mounted on a vehicle. The present invention relates to a regulator with a protection circuit.

[0002]

2. Description of the Related Art As a power source of a vehicle, a battery and an alternator (generator) are usually mounted. The alternator is driven by the engine to generate power, supply power to various vehicle loads, and charge the battery. Since the number of revolutions of the engine constantly changes depending on the operation state of the vehicle, the voltage generated by the alternator also changes accordingly. However, since it is necessary to supply a predetermined voltage to the vehicle load, the alternator is provided with a regulator for controlling the field current and controlling the generated voltage to a predetermined value.

[0003] However, if an accident such as a short-circuit of the field coil to the vehicle body occurs, the regulator cannot control the field current, and the voltage generated by the alternator may become excessive. Then, an excessive current flows into the vehicle load and the battery, and if left as it is, an accident such as burning of the vehicle load or breakage of the battery will eventually occur. Therefore, a regulator with an overvoltage protection circuit has been proposed in which an overvoltage protection circuit that turns off the field current when the voltage of the alternator becomes overvoltage is added to the regulator.

FIG. 3 is a diagram showing such a conventional regulator with an overvoltage protection circuit. In FIG. 3, 1 is an alternator, 2 is a power generation coil, 3 is a field coil, 4 is a neutral point, 5 is a rectifier circuit, 6 and 7 are rectification output terminals, 8 is a diode, 9 is a regulator with an overvoltage protection circuit, 10 is a diode, 11 is a transistor, 12 is a voltage control circuit,
13 is a regulator, 14 is an overvoltage protection circuit, 15 is a transistor, 16 is a charge lamp control circuit, 17 is a transistor, 18 is a battery, 19 is a key switch,
0 is a charge lamp.

The charge lamp 20 includes a key switch 19
Is turned on when the voltage at the neutral point 4 of the alternator 1 is smaller than a predetermined value while the switch is on. When the key switch 19 is turned on, an operating voltage is applied to the charge lamp control circuit 16. Since the alternator 1 has not yet generated power, the voltage at its neutral point 4 is zero. Therefore, the charge lamp control circuit 16
Turns on the transistor 17 and turns on the charge lamp 20.

Although the operating voltage is also applied to the overvoltage protection circuit 14, the alternator 1 has not yet started to generate power, and the output voltage is, of course, not an overvoltage. In this case, the transistor 15 is turned on.
On the other hand, a field current starts flowing through the field coil 3 of the alternator 1 through the following path. Battery 18 → key switch 19 → diode 8 → transistor 15 → field coil 3 → transistor 11 → battery 18. When the alternator 1 starts power generation and the voltage at the neutral point 4 becomes larger than a predetermined value, the charge lamp control circuit 16 turns off the transistor 17 and turns off the charge lamp 20.

The voltage generated by the alternator 1 is supplied to a rectifier circuit 5
And direct current is taken out from the rectification output terminals 6 and 7. The DC extracted from the rectification output terminal 6 is supplied to the battery 18 to charge the battery 18 and is also supplied to a vehicle load (not shown). Further, the DC taken out from the rectification output terminal 7 is used for controlling the alternator 1. The voltage control circuit 12 controls the transistor 11 so that the DC output voltage extracted from the rectification output terminal 7 has a predetermined value. That is, if the output voltage increases, the transistor 1
When the output voltage decreases, the internal resistance of the transistor 11 is reduced to increase the field current.

The overvoltage protection circuit 14 turns off the transistor 15 and cuts off the field current when the DC output voltage taken out of the rectification output terminal 7 exceeds a preset overvoltage. As a result, the alternator 1 stops generating power, so that overvoltage protection is performed. When the power generation voltage of the alternator 1 disappears, the voltage of the neutral point 4 also decreases, so that the charge lamp control circuit 16 restarts the transistor 1
7 is turned on, and the charge lamp 20 is turned on. Lighting of the charge lamp 20 indicates that the alternator 1 has stopped generating power.

By the way, the voltage generated by the alternator 1 is
It may increase instantaneously for some reason. When the overvoltage protection circuit 14 detects an overvoltage, it stores the fact and keeps turning off the transistor 15. Therefore, even with the above transient overvoltage, the power generation of the alternator 1 continues to be stopped, and the charge lamp 20 continues to light. The release of the memory is performed by turning off the key switch 19 and cutting off the operating voltage of the overvoltage protection circuit 14.

However, since a transient overvoltage does not cause burnout of a vehicle load, if the overvoltage protection circuit 14 operates in response to such a voltage, from the standpoint of protection of the vehicle load and the like. It is a malfunction. In order to distinguish such a malfunction from a continuous overvoltage to be truly protected, the key switch 19 is turned off once, turned on again, and checked again. If a continuous overvoltage has occurred, the charge lamp 20 will turn on again and the charge lamp 20 will light up, and if there is a transient overvoltage, the charge lamp 20 will not turn on. . A distinction is made by this difference.

[0011] As a conventional document relating to overvoltage of a vehicle power supply, there is, for example, Japanese Patent Application Laid-Open No. 2-197299.

[0012]

(Problems to be Solved) However, the conventional regulator with an overvoltage protection circuit described above, when the charge lamp 20 is turned on, may be caused by overvoltage or malfunction (transient overvoltage). There is a problem that the key switch 19 to which other vehicle loads are connected must be turned off and on each time in order to check whether or not the vehicle load is valid.

(Explanation of Problems) Turning off the key switch 19 means shutting off the power supply of all vehicle loads. Therefore, it is desirable to avoid doing this during use of the vehicle as much as possible. . However, in the conventional technique, every time the charge lamp 20 is turned on, it is necessary to shut off the power to confirm whether the cause of the overvoltage is transient. An object of the present invention is to solve the above problems.

[0014]

Means for Solving the Problems In order to solve the above problems, according to the present invention, there is provided a regulator for controlling a generated voltage, and an overvoltage for detecting an overvoltage of the generated voltage and storing the detected voltage to cut off a field current. a protection circuit, the charge lamp control circuit and an overvoltage protection circuit with regulator equipped with to light detected and charge lamp a drop in generated voltage due to the blocking, in the path for supplying the operating voltage of the overvoltage protection circuit, said A reset switch for canceling the storage is provided.

[0015]

[Operation] In a regulator with an overvoltage protection circuit including an overvoltage protection circuit for storing an overvoltage detection state, a reset switch is provided in a path for supplying an operating voltage of the overvoltage protection circuit, and the storage is released by turning off a key switch. Instead, this is done by turning off the reset switch. Therefore, when determining whether the detected overvoltage is a transient overvoltage, it is not necessary to turn off the key switch each time, and it is possible to avoid interruption of the operation of another vehicle load.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a regulator with an overvoltage protection circuit according to the present invention. In FIG. 1, reference numerals correspond to those in FIG. 3, 14-1 is an overvoltage display control unit, 21 is an overvoltage display lamp, and 22 is a reset switch. Those having the same reference numerals as those in FIG. 3 operate in the same manner, and a description thereof will be omitted.

The first point, which is different from the conventional example in FIG. 3, in that the overvoltage protection circuit 14 is provided with an overvoltage display control section 14-1 and the overvoltage display lamp 21 whose lighting is controlled by the overvoltage protection circuit 14 is provided. It is. The second point is that a reset switch 22 is provided to enable the storage of the overvoltage detection information of the overvoltage protection circuit 14 to be canceled without turning off the key switch 19. The reset switch 22
It is provided in the middle of a path for supplying an operating voltage to the overvoltage protection circuit 14 via the key switch 19.

(Operation when Overvoltage Occurs) When an overvoltage is detected by the overvoltage protection circuit 14, the transistor 15 is turned off and the overvoltage display lamp 21 is turned on. With the storage function of the overvoltage protection circuit 14, the off state of the transistor 15 and the lighting state of the overvoltage display lamp 21 are maintained. On the other hand, transistor 1
By turning off 5, the field current flowing through the field coil 3 disappears, so that the alternator 1 stops power generation and the voltage at the neutral point 4 decreases. Therefore, the charge lamp control circuit 1
6 turns on the transistor 17, and the charge lamp 20 is turned on.

(Distinction from Transient Overvoltage) A transient overvoltage that instantaneously becomes an overvoltage causes an overvoltage protection circuit 1.
In order to distinguish whether or not 4 operated (malfunction),
The reset switch 22 is turned off. Reset switch 2
Since the operating voltage of the overvoltage protection circuit 14 is cut off by turning off 2, the storage of the overvoltage detection is released. for that reason,
The transistor 15 returns to ON, and the overvoltage indicating lamp 21
Also goes back off. The reset switch 22 is configured to be immediately turned back on.

If a transient overvoltage occurs, the same overvoltage does not occur when the reset switch 22 is turned on. Therefore, the transistor 15 is not turned off, and the overvoltage indicating lamp 21 is not turned on. If the overvoltage has been generated due to the ground short-circuit of the field coil 3 or the like, the same overvoltage is generated again when the reset switch 22 is turned on. Accordingly, the transistor 15 is turned off, the charge lamp 20 is turned on, and the overvoltage display lamp 21 is also turned on. This makes it possible to distinguish whether or not a transient overvoltage has occurred.

(Distinction between Power Generation Failure and Overvoltage Accident) If the power generation voltage of the alternator 1 does not increase simply due to a failure of the alternator 1 or the regulator 13, the charge lamp control circuit 16 sets the transistor Turn on 17 and charge lamp 20
Lights up. However, since an overvoltage does not occur, the overvoltage protection circuit 14 does not operate, and the overvoltage display lamp 21 does not light. That is, when the overvoltage occurs, both the charge lamp 20 and the overvoltage display lamp 21 are turned on, but when the power generation is poor, only the charge lamp 20 is turned on, so that the distinction can be made.

FIG. 2 shows a detailed circuit diagram of a regulator with an overvoltage protection circuit according to the present invention. The reference numerals correspond to those in FIG. 1, and 23 is a thyristor. The thyristor 23 in the overvoltage protection circuit 14 is turned on when an overvoltage is detected, and performs a storage operation of the overvoltage detection state. Reset switch 22
Is turned off, the thyristor 23 is turned off, and the storage operation is released.

[0023]

As described above, according to the regulator with an overvoltage protection circuit of the present invention, not the key switch but the overvoltage protection circuit is used to determine whether or not the detected overvoltage is a transient overvoltage. , The operation of the vehicle load is not interrupted each time the determination is made.

[Brief description of the drawings]

FIG. 1 is a diagram showing a regulator with an overvoltage protection circuit according to the present invention.

FIG. 2 is a detailed circuit diagram of a regulator with an overvoltage protection circuit according to the present invention.

FIG. 3 shows a conventional regulator with an overvoltage protection circuit.

[Description of Signs] 1. Alternator, 2. Generating coil, 3. Field coil,
4: Neutral point, 5: Rectifier circuit, 6, 7: Rectifier output terminal, 8
... diode, 9 ... regulator with overvoltage protection circuit, 1
0: diode, 11: transistor, 12: voltage control circuit, 13: regulator, 14: overvoltage protection circuit, 1
4-1: Overvoltage display control unit, 15: transistor, 16
... charge lamp control circuit, 17 ... transistor, 18
... Battery, 19 ... Key switch, 20 ... Charge lamp, 21 ... Overvoltage display lamp, 22 ... Reset switch, 23 ... Thyristor

Continued on the front page (72) Inventor Taizo Kaneko 1-12-11 Higashirokugo, Ota-ku, Tokyo Nikko Electric Industry Co., Ltd. (72) Inventor Kazunari Toyome 1-12-11 Higashirokugo, Ota-ku, Tokyo (56) References JP-A-49-124509 (JP, A) JP-A-61-76016 (JP, A) JP-A-4-236120 (JP, A)

Claims (1)

(57) [Claims] A regulator for controlling a generated voltage, an overvoltage protection circuit for detecting an overvoltage of the generated voltage and storing the detected voltage to shut off a field current, and detecting a decrease in the generated voltage due to the cutoff. In a regulator with an overvoltage protection circuit including a charge lamp control circuit for lighting a charge lamp, a reset switch for canceling the memory is provided in a path for supplying an operating voltage of the overvoltage protection circuit. Regulator with overvoltage protection circuit.