JPH0212618Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a battery voltage monitoring device, in particular, when the engine is running, the alternator rotates to charge the battery and supply DC power to the load. The present invention relates to a battery voltage monitoring device configured to prevent this from occurring.

Generally, a car is equipped with a battery, and an alternator driven by the engine is connected in parallel to the battery.When the engine is running, the battery is charged by the alternator's generated output, and the load is also supplied with direct current. Electric power is being supplied, but when the engine is stopped, DC power is supplied to the load using only the output of the battery.

Therefore, as long as the engine is running, the alternator rotates and generates electricity, so there is enough power to supply each load, but the engine is stopped for a long time, and during that time, power is not supplied from the battery to the loads. If this continues for a long time, the battery will inevitably over-discharge and voltage recovery will become impossible. Therefore, it is necessary to take care to prevent the battery from becoming over-discharged by detecting the battery voltage state.

The present invention was developed with the aim of solving the above problems.While the battery maintains the specified voltage, the switch is closed, supplying DC power to the load, and reducing the battery voltage. It is an object of the present invention to provide a battery voltage monitoring device which opens a switch when voltage drops below a specified value and further displays an abnormality display. The purpose of this invention is to correctly guarantee the voltage that should give a difference between the closing voltage at which the switch is turned on and the opening voltage at which the switch is opened, by the forward voltage drop of the diode. Examples will be described below with reference to the drawings.

The figure shows a circuit diagram of an embodiment of the battery voltage monitoring device according to the present invention.

A battery voltage monitoring device according to one embodiment of the present invention consists of a voltage monitoring circuit section A and a timer circuit section B. In the figure, 1 is an alternator (which rectifies AC output and supplies DC voltage) and is driven by an engine (not shown). Reference numeral 2 denotes a battery, which is connected in parallel with the alternator 1 and connected to the battery power supply terminals T ₁ and T ₂ , and supplies DC power to a load (not shown) via load side output terminals T ₃ and T ₄ connected to the other. supply Reference numeral 3 denotes a switch which opens and closes in conjunction with a relay 4. 5 to 7 are switching transistors. 8 is a timer. 9 and 10 are diodes. 11 is a light emitting diode, for example, 11 emits red light, and 12
is a light emitting diode corresponding to the branch circuit referred to in this specification, and emits, for example, blue light. 13,14
is a zener diode. 15 to 29 is resistance.
30 to 36 are capacitors. A ₁ to a ₆ represent each terminal of the timer 8, and b ₁ and b ₂ represent voltage dividing points, respectively. Note that a resistor can be inserted into the series circuit of the diodes 9 and 11 if necessary.

Now, considering the state in which the engine is being driven, in this case, the alternator 1 is being rotated by the engine (not shown) to generate electricity (normally, when the engine is being driven, a voltage of 12.75±0.25V is generated, for example). The voltage divides resistors 19, 20, 2 through the diode 9 and the light emitting diode 11.
A current flows through the voltage dividing point b1, and a voltage corresponding to the voltage dividing ratio is generated at the voltage dividing point _b1 . Here, since the Zener diode 13 connected to the voltage dividing point b ₁ is set to be turned on by the divided voltage (the Zener diode _{13 is}
It turns off at about 10.75±0.5V. ), capacitor 3
After a charging time corresponding to the capacity of transistor 2, a base current is supplied to switching transistor 6 to turn it on.
When switching transistor 6 is turned on, the emitter of switching transistor 5 also turns on.
A current flows between the bases, turning on the transistor 5, energizing the relay 4 inserted in the collector circuit, and then energizing the relay 4 to close the switch 3 interlocked therewith. Therefore, DC power is supplied to a load (not shown) via the load side output terminals T ₃ and T ₄ . When the switch 3 closes, the light emitting diode 12 connected to the load side of the switch 3 is connected to the voltage dividing resistors 19, 20, 21, and 22. The current flowing through light emitting diode 1
It flows through the circuit side consisting of one of the two. This causes the light emitting diode 11 to stop emitting light, causing the light emitting diode 12 to emit blue light, and indicating that the power supply voltage is at the specified value.

Then, when the battery 2 discharges while the alternator 1 is stopped and the voltage between the terminals T ₃ and T ₄ becomes, for example, 10.75V or less, the switch 3 is opened. Also, the difference between the closing voltage at which the switch 3 is closed and the open circuit voltage at which the switch 3 is opened is determined by the diode 9,
This is guaranteed by the difference in voltage drop between 11 and diode 12.

On the other hand, in the timer circuit section B, a divided voltage according to the voltage dividing ratio of the voltage dividing resistors 23, 24, and 25 is generated at the voltage dividing point _{b2 .} The Zener diode 14 is connected to the power supply terminal T ₁ ,
It is set to be turned on when the voltage of T ₂ is, for example, 12.5V or higher (the voltage of the above terminals T ₁ and T ₂ will not drop below 12.5V when the engine is running), and therefore The diode 14 turns on and supplies the base current of the switching transistor 7, turning it on and stopping the timer function in order to ground the terminal _a1 of the timer 8.

There are many cases where the driver leaves the scene with the engine turned off and the transceiver or radio turned on, for example.
For example, when the engine is stopped, the battery voltage decreases.
Drops below 12.5V. Therefore, the Zener diode ₁₄ connected to the voltage dividing point b2 is turned off at the same time as the engine stops, but the switching transistor 7 is turned off after waiting for the discharge time by the capacitor 33.
is turned off. At the same time as the switching transistor 7 is turned off, a voltage is applied to the terminal _a1 of the timer 8, and the timer 8 is started. Note that the time setting of the timer 8 can be arbitrarily set by the time constant of the resistor 29 and the capacitor 34.

For example, if the time is set to one hour, the terminal _a6 of the timer 8 is grounded after the set time has elapsed. Therefore, the switching transistor 6 in the voltage monitoring circuit A is controlled by the diode 10.
The base circuit of is grounded to turn off the switching transistor 5, release the energization of the relay 4, and open the switch 3 linked thereto to prevent the battery 2 from overdischarging. Of course the above timer 8
Even within the set time, if the voltage at the power supply terminals T ₁ and T ₂ drops below the above 10.75V, the Zener diode 13 is turned off and the relay 4 opens the switch 3. In any of the above cases, when the switch 3 is opened, the current from the battery 2 flows through the diode 9.
and a resistor 19 through the circuit of the light emitting diode 11,
20, 21, 22, and the light emitting diode 1
1 to emit red light to indicate overdischarge (diode 12 stops emitting blue light).

When the driver returns and the engine is started,
When the engine is running, the terminal voltage is 12.5V above.
In order to achieve the above, the switch 3 is closed as described above and DC power is supplied to the load, and at the same time, the Zener diode 14 in the timer circuit section B is turned on, and then the switching transistor 7 is turned on, and the terminal of the timer 8 is turned on. _a1 is grounded and the timer 8 is reset. It goes without saying that the timer 8 is reset even if the timer 8 is in the middle of operation or after the operation is completed.

As explained above, according to the present invention, a switch is inserted between the power supply terminal and the output terminal, and a series circuit consisting of a diode and a light emitting diode is connected to the power supply side of the contact of the switch. The circuit configuration is such that a branch circuit, for example, one diode, is provided on the output side and each of the above is connected to a voltage divider circuit to monitor the voltage, so when the battery is over-discharged, the load is disconnected and the light emitted from the light-emitting diode is used to prevent over-discharge. It becomes possible to instruct the occurrence of a discharge state.

Further, the voltage difference between the voltage that closes the switch 3 and the voltage that opens the switch 3 is reliably applied by the difference between the voltage drop in the series circuit and the voltage drop in the branch circuit.

[Brief explanation of the drawing]

The figure shows a circuit diagram of the battery voltage monitoring device according to the present invention. In the figure, 1 is an alternator, 2 is a battery, 3 is a switch, 4 is a relay, 5 to 7 are switching transistors, 8 is a timer, 9 and 10 are diodes, 11 and 12 are light emitting diodes, 13,
14 is a Zener diode, 15 to 29 are resistors _, 30 to 36 are capacitors, a1 to _a3 are _each terminal of timer 8, _b1.b2 are voltage dividing points, A is a voltage monitoring circuit, B is a timer Each represents a circuit section.

Claims (1)

[Scope of utility model registration request] The vehicle is equipped with a vehicle power source consisting of an alternator driven by the engine and a battery charged by the alternator, and DC power is supplied from the vehicle power source to the load via a battery voltage monitoring circuit. In the battery voltage monitoring device, the battery voltage monitoring circuit section includes a switch inserted between the battery power supply terminal and the output terminal, a diode and a light emitting diode connected in series to the power supply side of the contact of the switch. a series circuit and a branch circuit provided on the output terminal side; a voltage dividing resistor connected to an intersection on the output side of the series circuit and the branch circuit;
A switching transistor is connected to a voltage dividing point of the voltage dividing resistor via a Zener diode, and a relay is energized by the operation of the switching transistor. A battery voltage monitoring device characterized in that it is configured to cause the switch to open and close.