JPH03273817A - Apparatus for avoiding overdischarge of battery of unattended carriage - Google Patents

Abstract

PURPOSE:To avoid gas generation and overdischarge wear caused by the reversing of a battery by a method wherein it is detected that the discharge of the battery reaches a predetermined limit and an electric path between the battery and a load is shut off. CONSTITUTION:The terminal voltage of a battery 1 is applied to a comparing input terminal S2 through the normally-open contacts 8a1 and 9a2 of second and third relays 8 and 9 which are connected in parallel to each other. A reference voltage immediately before the discharge limit of the battery 1 is applied to one reference input terminal S1 and the terminal voltage is compared with the reference voltage and, normally, the third relay 9 is excited. If the terminal voltage of the battery 1 is declined below the reference voltage, the excitation of the third relay 9 is demagnetized and an electric path to a load 2 is shut off. With this constitution, gas generation and overdischarge wear caused by the reversing of the battery 1 can be prevented. Further, as the terminal voltage of the battery 1 is elevated immediately after the load 2 is cut off by the parallel connection of the contacts 8a1 and 9a2, the malfunction of the apparatus can also be avoided.

Description

[Detailed Description of the Invention] [Industrial Application Field] In an automatic guided vehicle that automatically travels along a specific route on the floor, when the workplace where the vehicle is placed is in use 24 hours a day, the automatic guided vehicle automatically travels along a specific route on the floor. If automatic travel of the automatic guided vehicle is hindered due to obstacles, etc., the battery of the automatic guided vehicle becomes over-discharged.

In such a case, if the battery is left unattended without being aware of the condition, the battery will generate gas due to polarity reversal.

If this condition continues, the battery will wear out and its lifespan will be shortened, and if the automated guided vehicle equipped with the battery is placed in a clean room and operating, the gas generated will be released into the indoor air. It becomes a troublesome situation as it contaminates the water.

The present invention provides an over-discharge prevention device for a battery of an automatic guided vehicle in consideration of avoiding such a situation.

[Conventional technology] The conventional one was constructed as shown in Figure 2.

In the figure, 1 is a battery that serves as a driving power source for the automatic guided vehicle, and 2 is a load consisting of a control power source, a motor, and the like. 3
is a normally open type power switch, 4 is a relay, 4
a is a normally open contact of relay 4;

5 is a voltage detector that detects the terminal voltage of battery 1, 6
is an alarm device such as a buzzer that issues an alarm when the terminal voltage of the battery reaches the reference voltage ■0, which is just before over-discharge.

In the above configuration, when the power switch 3 is turned on, the relay 4 is energized and its contact 4a is turned on, and power is supplied from the battery 1 to the load 2.

The automated guided vehicle automatically travels in a predetermined manner according to the route.

At this time, if the automatic guided vehicle becomes unable to travel due to the presence of obstacles in the passage, etc., and the battery 1 becomes over-discharged, and this state is detected via the voltage detection means 5, the alarm 6
issues an alarm.

[Problems to be Solved by the Invention] In the conventional system, even if an overdischarge condition occurs, the alarm device 6 simply notifies the user of this by an alarm, so that the operator cannot hear the alarm.

Unless the circuit with the load 2 is interrupted, the discharge of the battery 1 will continue, eventually reaching an undesirable situation in which gas is generated due to polarity reversal.

This is because automated guided vehicles operate 24 hours a day, and during late night work when there are no operators between the vehicles.

Since this problem often occurs, this countermeasure was required.

An object of the present invention is to provide an overdischarge prevention device for a battery of an automatic guided vehicle, which solves the above-mentioned conventional problems.

[Means for Solving the Problems] According to the present invention, when it is detected that the battery of an automatic guided vehicle has reached a predetermined discharge amount due to the occurrence of an abnormal situation, the electric path from the battery to the load is cut off by this detection. The battery overload prevention device of the automatic guided vehicle is installed.

In this case, the first relay 4. Normally open contact 8 of each second and third relay
al, 9a+ connected in parallel and connected in series, and a second relay 8 and capacitor 6 connected in series via the power switch 3 are connected in parallel to the battery 1, respectively, and the capacitor is connected in parallel to the battery 1. A resistor 7 for discharging and a normally closed type power switch 3' that opens and closes in conjunction with the power switch 3 are connected in parallel to 6, and an overdischarge voltage having a comparison input terminal and a reference input terminal is connected in parallel. In the determination device, the terminal voltage of the battery is applied to the comparison input terminal through the normally open contacts 8a2 and 9az of the second and third relays connected in parallel, and the terminal voltage of the battery is applied to one reference input terminal. Add the reference voltage just before the discharge limit.

A battery for an automatic guided vehicle configured to compare the pressures of both types and normally energize a third relay, but to eliminate the energization of the third relay when the terminal voltage of the battery drops below a reference voltage. It can be used as an overload protection device.

[Example] The present invention will be specifically described below with reference to an example shown in FIG.

In the same figure, components equivalent to the conventional one are indicated by the same reference numerals as those in FIG.
For convenience of explanation, will be referred to as the first relay.

3' is a normally closed type power switch that operates in conjunction with the power switch 3.

6 is a capacitor that sets the time until the voltage of the battery 1 is supplied to the load 2, and 7 is a resistor for discharging the capacitor 6.

8 is a second relay, and 8a1 and 8az are normally open contacts of the second relay 8, respectively.

9 is a third relay, and 9a1 and 9a2 are normally open contacts of the third relay 9, respectively.

Reference numeral 10 denotes an overdischarge voltage determiner, which is composed of, for example, a comparator, and the voltage just before the battery 1 becomes overdischarged is applied to its reference input terminal S1 as a reference voltage 0, and the voltage is applied to its comparison input terminal S2. Compare the terminal voltage of the battery given through the detector 5 and turn off the third relay 9 when the terminal voltage of the battery 1 becomes low.
It has the function of

Note that E is a terminal of a control power source.

[Operation] When the power switch 3 is turned on, the second relay 8 is energized, its contacts 8a1 and 8a2 are turned on, and the first relay 4 is energized. (in this case.

(The power switch 3' is turned OFF).

By energizing the relay 4, its contact 4a is turned on, and DC power from the battery 1 is supplied to the load 2.
The automated guided vehicle starts the required automatic travel.

On the other hand, when the contact 8a2 turns ON, the overdischarge voltage determiner 10 is activated and starts comparing the reference voltage with the terminal voltage of the battery 1. Since the terminal voltage is higher, the third relay 9 is energized, and its contacts 9a1 and 9a
z is ON.

On the other hand, the capacitor 6 starts charging when the power switch 3 is turned on, and when the charging is completed, the excitation current of the second relay 8 disappears, so the contacts 8a++ and 8az of the relay are turned OF.
It becomes F.

In addition, the terminal voltage of the battery 1 is discharged as the automated guided vehicle continues to automatically travel or carry out cargo handling operations, but as mentioned above, for example, when there is an obstruction on the route of the automated guided vehicle, teeth.

As a result, the automatic guided vehicle becomes unable to travel, and the battery 1 is significantly discharged, and the voltage at the terminals of the battery drops to the standard voltage VO.

Therefore, in this case, the output of the overdischarge voltage determiner disappears, and the relay 9 is no longer energized, so the contact 9 of the relay
a l+ 9 a 2 is turned OFF.

Since the first relay 4 loses excitation by turning off the contact 9 a +, the contact 4 a is turned off and the battery 1 is turned off.
The supply of DC power to the load 2 is stopped, and the battery 1 is prevented from being over-discharged below the standard voltage Vo.

When the above-mentioned abnormal condition is restored and the power is turned on, first turn off the power switch 3, and then turn the power switch 3'
is turned on to discharge the charging voltage of the capacitor 6 via the resistor 7, and then the power switch 3 is turned on again. The subsequent operations are as described above, so they will not be repeated.

In the circuit shown in FIG. 1, the contacts 8a2+9 of the second relay 8 and the third relay 9 are connected before and after the overdischarge voltage determiner 10.
The reason why a2 are connected and inserted in parallel is as follows.

That is, if these contacts 8a2 and 9a2 do not exist, the terminal voltage of the battery 1 increases when the load' is no longer flowing. 4 is removed and its contact 4a is turned OFF.

Therefore, before the load 2 is disconnected, the terminal voltage of the battery 1 becomes higher than the standard voltage Vo, and when the third relay 9 is energized, this sushi-9 is alternately energized and de-energized. This repeatedly causes a so-called chattering phenomenon.

However, if each of the contacts 8a2 and 9a2 exists as described above, the contact 8a2 will turn off when the capacitor 6 is fully charged.
After reaching F, the contact 9a2 de-energizes the relay 9 due to over-discharge detection by the determiner 10.
Since it becomes F, relay 9 will no longer be excited,
Therefore, the chattering phenomenon described above is prevented.

[Effects of the Invention] As described above, the present invention cuts off the power supply path to the load by detecting over-discharge of the battery by cleverly connecting electric elements such as three relays, their contact capacitors, and a discharge voltage determiner. Since it is made as follows, it has an excellent first-order effect.

■When the battery reaches a specified over-discharge state.

It is immediately detected and the electrical circuit to the load is cut off.

(2) Therefore, as the over-discharge state of the battery progresses, the generation of gas due to polarity reversal and the wear and tear of the battery due to excessive over-discharge, which conventionally occur, are prevented.

■It should be noted that there is a second circuit in front of the overdischarge voltage determination circuit. Because the contacts of the third relay are connected in parallel.

Immediately after the battery disconnects the load, its terminal voltage increases, which also prevents the device from malfunctioning.

[Brief explanation of drawings]

FIG. 1 is a connection diagram showing one embodiment of the present invention, and FIG. 2 is a connection diagram of a conventional example. 1: Battery 2: Load 33': Power switch 4.8, 9: 1st. Second and third relay 4a: First relay contacts 8a1, 8az: Second relay contacts 9a++ 9a2: Third relay contacts 5: Overdischarge voltage determiner 6: Capacitor 7: Discharge resistor

Claims (1)

[Scope of Claims] 1. When it is detected that the battery of the automatic guided vehicle has reached a predetermined discharge amount due to the occurrence of an abnormal situation, the electric path from the battery to the load is cut off based on this detection. An automatic guided vehicle battery overload prevention device featuring: 2. The first power supply via the normally open type power switch 3.
relay 4 and normally open contacts 8a of each of the second and third relays.
_1, 9a_1 connected in parallel, connected in series, and the second relay 8 and capacitor 6 connected in series via the power switch 3 are connected in parallel to the battery 1, respectively. A resistor 7 for discharging and a normally closed type power switch 3' which opens and closes in conjunction with the power switch 3 are connected in parallel to the capacitor 6, and an overvoltage circuit having a comparison input terminal and a reference input terminal is connected in parallel. The discharge voltage determiner applies the terminal voltage of the battery to the comparison input terminal through the normally open contacts 8a_2 and 9a_2 of the second and third relays connected in parallel, and one of the reference input terminals A reference voltage just before the battery's discharge limit is applied, the two voltages are compared, and the third relay is normally energized, but when the battery terminal voltage drops below the reference voltage, the third relay is energized. An overload prevention device for a battery of an automatic guided vehicle, characterized in that the device is configured to eliminate the