JPH03279883A - Overdischarge detecting device for battery on unmanned carriage - Google Patents

Abstract

PURPOSE:To detect overdischarge by providing voltage detecting means to respective minimum units of plural cells constituting the battery and detecting one of the voltage detecting means dropping below a specific voltage. CONSTITUTION:The respective cells 2a1 - 2an which constitute the battery 1 are provided with (n) voltage detectors 4a1 - 4an so as to detect their terminal voltages and a detection output '1' is generated when the voltage of one cell drops below the specific voltage. An OR element 5 inputs the outputs of the detectors 4a1 - 4an and an alarm 6 operates with the output of the element 5. If the battery in use is overloaded and one of the cells constituting the group battery, e.g. cell 2a2 is overdischarged and then inverted in polarity to discharge gaseous hydrogen, its terminal voltage is detected by the voltage detector 4a2. An output '1' indicating this abnormal state is sent to the element 5, which operates the alarm 6 to warn the overdischarge.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in an over-discharge detection device for a battery mounted on an automatic guided vehicle and used as a driving source thereof.

[Prior art] As shown in Fig. 2, in the conventional technology, the battery mounted on one automatic guided vehicle has n cells 2a + to 2.
a, are connected in series to form an assembled battery. For example, in the case of a lead-acid battery, 1 cell is 2■, so there are 12 cells.
For nickel-cadmium storage batteries, each cell has a capacity of 1.2 µm, so 20 batteries are connected in series.

The assembled batteries are connected to each other so that the voltage is 24V.

Generally, when a battery continues to discharge beyond its discharge end voltage, the terminal voltage becomes OV.

Eventually, the voltage will reverse polarity and generate gases such as hydrogen and oxygen, which will damage the battery.

In such a state, the electrolyte becomes atomized and is released into the surroundings, damaging surrounding electrical equipment and the like. Therefore, it is necessary to provide over-discharge detection means to prevent the battery from over-discharging.

3 is a voltage detector as this over-discharge detection means.

It is connected to detect the terminal voltage of the battery 1 as an assembled battery.

Then, over-discharge detection of the battery is performed as follows.

That is, it is assumed that each cell constituting one set of batteries has sufficiently uniform characteristics, and if the discharge end voltage of one cell battery is 2, then the overdischarge voltage 2 becomes V = n x V w .

However, n is the number of cells.

When the total voltage reaches the above voltage ■, this battery battery 1
ends the discharge, issues an alarm, or turns off the source voltage.
It was.

[Problems to be Solved by the Invention] By the way, in the case of such an assembled battery consisting of a plurality of cells, the actual situation is that the discharge characteristics of each cell are not uniform. As shown in FIGS. 3(A) to 3(C), there are variations in the discharge characteristics.

Therefore, considering the operating state of an automatic guided vehicle equipped with such a battery, at one time point 1+, cell S2 or S shown in (b) or (c) can still be discharged, but ( The cell S1 shown in (a) has exceeded the discharge end voltage and is in an overdischarge state, and if left until this point, it is dangerous because hydrogen gas will be generated due to polarity reversal.

The discharge tt pressure of a battery decreases as it discharges, and its characteristics vary depending on temperature, discharge current,
It has been difficult to accurately determine the discharge end voltage because it varies depending on the mode of use, such as continuous use or intermittent use.

In other words, with the conventional one! The pressure detector 3 monitors the total voltage of the battery and detects when the value becomes abnormal. At the initial stage when cells generate hydrogen gas due to overdischarge, the abnormal condition cannot be detected and is detected only after many cells are overdischarged, leaving the abnormality as described above unresolved. There was a problem.

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

[Means for Solving the Problems] The present invention includes a voltage detection means for detecting voltage for each minimum unit of a plurality of cells that constitute a battery that is mounted on an automatic guided vehicle and used as a drive source.

The present invention relates to an over-discharge detection device for a battery of an automatic guided vehicle, which detects over-discharge of a battery by detecting that any one of these voltage detection means has a value equal to or lower than a predetermined voltage.

In this case, it is desirable to provide an over-discharge detection device for a battery of an automatic guided vehicle that uses one cell for each cell as the minimum unit of a plurality of cells.

Further, the over-discharge detection device for a battery of an automatic guided vehicle may use a plurality of cells each having two or three cells connected in series as the minimum unit.

Further, the over-discharge detection device for a battery of an automatic guided vehicle may be provided with a polarity detection means instead of the voltage detection means.

Furthermore, it is desirable that the over-discharge detection device automatically shuts off a power switch inserted into the electrical circuit between the battery and the load based on the over-discharge detection signal.

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

Incidentally, in the figure, the same reference numerals as in FIG. 2 are given to the parts corresponding to the conventional ones.

4a+ to 4a n are n voltage detectors provided for each of the cells 2a+ to 2a n constituting the battery 1, respectively, to detect their terminal voltages, and when the voltage is higher than a predetermined voltage, [0] is set. , and outputs a detection output [1] when the voltage drops to a value below a predetermined voltage.

Reference numeral 5 denotes an OR element that receives the outputs of the voltage detectors 4 a + to 4 a R as inputs.

6 is an alarm activated by the output of the OR element 5. Note that instead of the voltage detectors 4a+ to J a n described above,
A polarity detector is provided to detect the polarity of the terminal voltage of each cell 2a+ to 2ah. For example, when the polarity is normal, [0
], and when the polarity is reversed, [1] may be output, and this signal may be sent to the OR element 5.

In addition, regardless of whether a voltage detector or a polarity detector is used, it is preferable to provide one for each cell as shown in this embodiment, but instead of this, two or three cells may be connected in series. A voltage or polarity detector may be provided for each distribution.

Note that instead of providing an alarm 6 to issue an alarm, a power switch (not shown) inserted into the electrical circuit between the battery 1 and the load may be automatically shut off based on the output of the OR element 5. desirable.

[Function] In the present invention, the battery mounted on the automatic guided vehicle and used as a driving source becomes overloaded due to the reasons described above, and one of the cells constituting one set of batteries, for example,
When the cell 2a2 becomes over-discharged and then reverses polarity and emits hydrogen gas, the voltage across the cell 2a2 is detected by the voltage detector 4a, so the output [1] indicating the abnormal state is detected. ] is sent to OR element 5, so OR element 5
immediately outputs output [1] and activates alarm 6.

Issues an alarm to notify of overdischarge.

This is exactly the same when the voltage detector is replaced by a polarity detector. In this case, the polarity detector detects the polarity change of the cell 2az and sends the alarm 6 via the OR element 5. It will work.

Therefore, one worker uses this alarm to disconnect the battery power source from the load to prevent further overdischarge.

Incidentally, if the power switch is operated by the output of the OR element as described above, the electric circuit is automatically cut off when overdischarge is detected.

In the above, if the voltage detector or polarity detector is installed to detect the terminal voltage of two or three cells together, the detection time will be later than that of one cell, but 2fli or 3 Since over-discharge of the first cell is detected early, the battery can be protected from over-discharge before it becomes abnormal, unlike conventional systems.

[Effects of the Invention] The present invention relates to an over-discharge detection device for a battery of an automatic guided vehicle in which a voltage detection or polarity detection means is provided for each minimum unit of cells constituting the battery of an automatic guided vehicle as described above. Therefore, it has the following excellent effects. 5. If there is an overdischarge in the smallest unit such as one or two of the cells that make up the battery, it will be detected immediately and an alarm will be issued or Can be cut off directly with the power switch.

■Therefore, it is possible to prevent abnormal conditions from progressing during the overdischarge stage of the cells, which are the smallest unit of the battery, and therefore prevent the generation of large amounts of hydrogen gas, acid fog, and alkaline fog, and prevent the battery from becoming abnormal. The lifespan can also be made longer than conventional ones.

[Brief explanation of drawings]

FIG. 1 is a connection diagram showing one embodiment of the present invention, and FIG. 2 is a connection diagram showing a conventional example. Figure 3 shows the discharge characteristics of the battery. 1: Battery a to 2a, Nicell 4 to 4 a7: Voltage detector or polarity detector 5: OR element 6: Alarm

Claims (1)

[Scope of Claims] 1. Voltage detection means for detecting voltage in each minimum unit of a plurality of cells constituting a battery mounted on an automatic guided vehicle and used as a drive source is provided, and these voltage detection means 1. An over-discharge detection device for a battery of an automatic guided vehicle, characterized in that over-discharge of a battery is detected by detecting that one of the voltages has a value equal to or lower than a predetermined voltage. 2. The over-discharge detection device for a battery of an automatic guided vehicle according to claim 1, wherein one cell is used for each cell as the minimum unit of the plurality of cells. 3. 2 or 3 cells each as the minimum unit of multiple cells
2. The over-discharge detection device for a battery of an automatic guided vehicle according to claim 1, which uses a device in which individual cells are connected in series. 4. The over-discharge detection device for a battery of an automatic guided vehicle according to any one of claims 1 to 3, further comprising polarity detection means in place of the voltage detection means. 5. The over-discharge detection device according to any one of claims 1 to 4, wherein a power switch inserted into the electrical circuit between the battery and the load is automatically cut off based on the over-discharge detection signal.