JPH07320791A - Battery system for unmanned carrying vehicle - Google Patents

Abstract

PURPOSE:To stop the discharge of a battery prior to generation of hydrogen gas in a battery system for unmanned carrying vehicle. CONSTITUTION:When even any one of terminal voltages of batteries 1-1-1-n becomes lower than a standard voltage 12, an output signal forming high level is supplied to an OR circuit 13 from the corresponding comparator of comparators 11-1-11-n. When even any one of the output signals of the comparators 11-1-1-n becomes high level, the output signal of the OR circuit 13 becomes also high level, and the exciting current supplied to a relay Ry1 through a contact SW1 is of by a relay driver 14. Since the relay RY1 is laid in the off state, consequently, the contacts Ry1', Ry2' of the relay Ry1 are laid in the off state to stop the discharge of the batteries 1-1-1-n, and generation of hydrogen gas can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery system for an automated guided vehicle that uses a sealed alkaline battery as a power source.

[0002]

2. Description of the Related Art In recent years, automatic guided vehicles have been used in clean rooms, which are facilities for manufacturing semiconductor integrated circuits and the like. This unmanned guided vehicle is often used as a power source of a sealed alkaline battery that can be rapidly charged. Even if it is a sealed alkaline battery, a safety valve is generally provided to release the internal pressure when the pressure inside the battery rises.

For example, in Japanese Patent Application No. 4-223397, a battery system of an automatic guided vehicle uses a plurality of sealed alkaline batteries (about 20 to 40) connected in series as an assembled battery, and one of them is used. A pressure sensor is attached to one or more cells to release hydrogen gas or alkali inside the battery when the pressure inside the battery rises. In particular, when the internal pressure rises due to hydrogen gas generated by over-discharge, or when the internal voltage rises due to over-discharge and the terminal voltage is changed from (+) to (-) and the internal pressure rises due to hydrogen gas, the clean room is contaminated. However, it is important to provide a safety valve because there is a risk that the yield of products (semiconductor integrated circuits, etc.) will be adversely affected.

[0004]

By the way, when a plurality of sealed alkaline batteries connected in series are used as an assembled battery as in the battery system of the automatic guided vehicle described above, the charging characteristics and discharge of each cell are improved. Due to variations in characteristics, it is not possible to confirm that the internal pressures of all cells are within the safe area unless a pressure sensor is provided for each cell. However, in the battery system of the conventional automatic guided vehicle,
Since it is necessary to attach the pressure sensor to all the cells of about 40 to 40 cells, there is a problem that the cost is increased.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a battery system for an automated guided vehicle that can stop the discharge of the battery before hydrogen gas is generated.

[0006]

In order to solve the above-mentioned problems, according to the invention of claim 1, in a battery system of an automatic guided vehicle equipped with a plurality of sealed alkaline batteries as an assembled battery, the plurality of sealed Detecting the terminal voltage of each of the sealed alkaline batteries, and when at least one terminal voltage falls below a predetermined reference voltage set to a voltage higher than the hydrogen gas generation voltage of the sealed alkaline battery, the plurality of sealed batteries A discharge stop control means for stopping the discharge of the alkaline battery to the load is provided.

Further, in the invention according to claim 2, the discharge stop control means is provided corresponding to the plurality of sealed alkaline batteries and detects a plurality of terminal voltages of the sealed alkaline batteries. A differential amplifier, a plurality of comparison means provided corresponding to the plurality of sealed alkaline batteries, and comparing each of the terminal voltages output by the plurality of differential amplifiers with the reference voltage; It is characterized by comprising an OR circuit for taking the logical sum of the outputs of the means, and a relay for opening the transmission path to the load of the plurality of sealed alkaline batteries based on the result of the logical operation of the OR circuit.

[0008]

According to the invention described in claim 1, the discharge stop control means detects the terminal voltage of each of the plurality of sealed alkaline batteries, and at least one terminal voltage is set to a voltage higher than the hydrogen gas generation voltage. When the voltage becomes lower than the predetermined reference voltage, the discharge to the load is stopped. Therefore, even if the charge / discharge characteristics of the plurality of sealed alkaline batteries vary, the discharge of the plurality of sealed alkaline batteries can be stopped before the hydrogen gas is generated, so that the generation of hydrogen gas can be prevented. .

According to the second aspect of the invention, the terminal voltage of each of the plurality of sealed alkaline batteries is detected by the plurality of differential amplifiers provided corresponding to each sealed alkaline battery. Next, each of the terminal voltages output by the plurality of differential amplifiers is compared with the reference voltage by a plurality of comparing means provided corresponding to the plurality of sealed alkaline batteries. At this time, when at least one terminal voltage becomes equal to or lower than the reference voltage, the result of the logical operation of the OR circuit becomes active, so that the relay opens the transmission paths to the loads of the sealed alkaline batteries.

[0010]

【Example】

A. Configuration of Embodiment Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a battery system for an automated guided vehicle to which the present invention is applied. In the figure, 1-
1, 1-2, ..., 1-n are single-cell sealed alkaline batteries (hereinafter, referred to as batteries), which are connected in series, and also have the (-) and (+) terminals of the battery 1-1. The (+) terminals of the cells of the batteries 1-2 to 1-n are connected to the battery voltage monitoring unit 6. Here, each battery 1-1 to
The voltages supplied from 1-n to the battery voltage monitoring unit 6 are V0, V1, V2, ..., Vn-1, Vn, respectively.

The (-) terminal of the battery 1-1 and the (+) terminal of the battery 1-n are connected to the power receiving coupler 2 of the automatic guided vehicle, and serve as a power source for each part of the automatic guided vehicle. It is connected to L. The power receiving coupler 2 is
When charging the batteries 1-1 to 1-n, they are fitted into a charging system (not shown) to supply a predetermined charging current to the batteries 1-1 to 1-n. Each of the batteries 1-1 to 1-n is provided with safety valves 3, 3, ..., 3 except one. The safety valve 3 operates as a safety device for preventing the explosion of the batteries 1-1 to 1-n due to over discharge.
When the safety valve 3 is opened, hydrogen gas, alkali, etc. accumulated inside the batteries 1-1 to 1-n are released to the outside.

Reference numeral 5 denotes an internal pressure detection sensor, which is a battery 1-3.
Is installed in place of the safety valve 3 and detects the internal pressure value of the battery 1-3. The internal pressure detection sensor 5 may be attached to any one or a plurality of the batteries 1-1 to 1-n. The contact SW1 provided inside the internal pressure detection sensor 5 is normally in the on state, while it is in the off state when the internal pressure of the battery 1-3 becomes a predetermined pressure value or more. .

One end of the contact SW1 is a relay Ry.
1 is connected to the coil and the other end is connected to a relay driver of the battery voltage monitoring unit 6 described later. The relay Ry1 is excited by a relay driver described later when the contact SW1 is in the ON state.
Further, the relay Ry1 has two contacts Ry1 ′ and Ry2 ′.
Is equipped with. The contact point Ry1 ′ of the relay Ry1 is interposed between the batteries 1-1 to 1-n and the power receiving coupler 2,
When the internal pressure of the battery 1-3 is less than or equal to the predetermined pressure value, the coil of the relay Ry1 is energized and therefore closed. The contact point Ry2 ′ of the relay Ry1 is connected to the battery 1-1.
~ 1-n and the load L is inserted, the contact Ry1 '
Like, it is usually closed.

Next, the configuration of the battery voltage monitoring unit 6 described above will be described with reference to FIG. FIG. 2 is a block diagram showing the configuration of the battery voltage monitoring unit 6. In the figure, 10-1, 10-2, 10-3, ..., 10- (n-1), 10-n
Is a differential amplifier that amplifies and outputs the difference between the input signals supplied to the two input terminals. In the differential amplifier 10-1,
The voltages V0 and V1 described above are supplied, and the differential amplifier 10-2 is supplied with the voltages V1 and V2. Less than,
Similarly, the voltages Vn-1 and Vn are supplied to the differential amplifier 10-n. That is, each differential amplifier 10-1 to 1
Each of 0-n detects the terminal voltage of the corresponding battery 1-1 to 1-n and outputs it.

Next, 11-1, 11-2, 11-3, ..., 11
-(n-1), 11-n are comparators that compare the input signal supplied to the input terminal with a predetermined reference voltage 12 and output the comparison result. The comparators 11-1 to 11-n are supplied with the outputs of the differential amplifiers 10-1 to 10-n corresponding to the comparators 11-1 to 11-n, respectively, and are supplied with a common reference voltage 12. That is, each of the comparators 11-1 to 11-n
Compares the terminal voltage of each battery 1-1 to 1-n supplied from the differential amplifier 10-1 to 10-n with the reference voltage 12,
When the terminal voltages of the batteries 1-1 to 1-n become equal to or lower than the reference voltage 12, the output signal of high level (“1”) is supplied to the OR circuit 13.

The OR circuit 13 includes the comparator 11-1.
11-n outputs the logical sum of the outputs, and supplies the result to the relay driver 14. In other words, if the output of any one of the comparators 11-1 to 11-n becomes high level, the output of the OR circuit 13 becomes high level. The relay driver 14 is the relay Ry1 described above.
Is supplied with an exciting current through a contact SW1,
When the output of the R circuit 13 becomes a high level, that is, any one of the batteries 1-1 to 1-n has a reference voltage of 12
When it becomes below, the exciting current is turned off.

Here, a method of setting the above-mentioned reference voltage 12 will be described with reference to FIGS. 3 and 4. FIG. 3 is a characteristic diagram showing discharge characteristics of an alkaline battery (both sealed and open type), and FIG. 4 is a discharge characteristic for explaining a problem that occurs when a plurality of alkaline batteries are used as an assembled battery. FIG. In FIG. 3, 0.2
The relationship between the terminal voltage and the discharge time when the battery is discharged at CA (current value of 20% of battery nominal capacity, current value of 2 A for 10 AH nominal capacity) is shown. In general,
As described above, the alkaline battery, regardless of whether it is a sealed type or an open type, is subjected to over-discharge, the terminal voltage is changed from (+) to (-), and hydrogen gas is generated. In the figure, hydrogen gas is generated when the terminal voltage becomes -0.2V. Also,
Hydrogen gas is generated from the terminal voltage of about 1V -0.2
It can be seen that up to V is discharged in a short time. Therefore, in order to prevent the generation of hydrogen gas, the discharge (power supply to the load L) may be stopped at about 1.1 to 0.8 V before the terminal voltage of the battery becomes −0.2 V. It will be.

On the other hand, when using a battery as an assembled battery, it is necessary to consider the variation in the discharge characteristics of each cell. For example, when the discharge stop voltage per cell is set to 1V, the total discharge stop voltage of the assembled battery composed of 20 cells is 1V × 20 = 20V. By the way, the variation in the discharge characteristics of each cell is generally about 10 to 20%. Therefore, when only one of the 20 cells has a discharge characteristic of 20% smaller, as shown in FIG. 4, the discharge characteristics of the 19 cells are as shown by the curve C1. On the other hand, the discharge characteristic of the 20% smaller cell is the characteristic shown by the curve C2.

In the figure, a cell having a small discharge characteristic generates a large amount of hydrogen gas after the discharge time of 5 hours. On the other hand, the other 19 cells do not generate hydrogen gas. The total voltage of the assembled battery at this time is 19 × 1.2V + 1 × (−0.2V) = 22.6V
Is. Therefore, as described above, if the total discharge stop voltage is simply set to 20 V, hydrogen gas will be generated from cells having variations in discharge characteristics (particularly cells having small discharge characteristics).

Therefore, in the present embodiment, the battery voltage monitoring unit 6 compares the terminal voltages of the batteries 1-1 to 1-n with the reference voltage 12 to determine the terminal voltages of the batteries 1-1 to 1-n. When any one of them becomes the reference voltage 12 or less, the discharge is stopped. In this case, batteries 1-1 to 1
-n terminal voltage, each is compared with the reference voltage 12,
It is determined whether or not each has reached the voltage for generating hydrogen gas. Therefore, the reference voltage 12 is set to a discharge stop voltage for one battery, that is, -0.2 V or higher (usually 1.1 to 0.8 V).

B. Operation of Embodiment Next, the operation of the above-described embodiment will be described. In the battery voltage monitoring unit, the terminal voltages of the batteries 1-1 to 1-n, that is, V1-V0 (terminal voltage of the battery 1-1), V
2-V1 (terminal voltage of battery 1-2), ..., Vn-Vn-1
(Battery 1-n terminal voltage) to differential amplifiers 10-1 to 10
Detect by -n. Then, the comparators 11-1 to 11-1
In 1-n, the terminal voltages of the batteries 1-1 to 1-n supplied from the differential amplifiers 10-1 to 10-n are compared with the reference voltage 12. Here, if any one of the terminal voltages of the batteries 1-1 to 1-n becomes equal to or lower than the reference voltage 12 (for example, 0.8 V), the corresponding one of the comparators 11-1 to 11-n becomes a high level. The output signal of (“1”) is supplied to the OR circuit 13.

If any one of the output signals of the comparators 11-1 to 11-n becomes high level, the output signal of the OR circuit 13 becomes high level and the relay driver 1
4, the exciting current supplied to the relay Ry1 via the contact SW1 is turned off. As a result, the relay Ry1 is turned off, so that the contacts Ry1 ′, R of the relay Ry1 are turned off.
The y2 'is turned off and the discharge of the batteries 1-1 to 1-n is stopped.

When the internal pressure of the battery 1-3 rises, the internal pressure detection sensor 5 detects the increase of the internal pressure as described in the prior art, the contact SW1 is turned off and the relay Ry1 is turned on. Stop the excitation current supply. Therefore, also in this case, since the relay Ry1 is turned off, the contacts Ry1 ′ and Ry2 ′ of the relay Ry1 are turned off and the discharge of the batteries 1-1 to 1-n is stopped.

In the above-described embodiment, the terminal voltage of each battery 1-1 to 1-n is detected and compared with the reference voltage 12, and the discharge to the load L is stopped before hydrogen gas is generated. , Is not limited to the configuration shown in FIG. 1 or FIG.
After detecting the terminal voltage of 1-n and converting it into a digital signal by an A / D converter through a multiplexer such as an analog switch, the output value of the above A / D converter is read by a microcomputer and the following comparison, The determination process may be processed by software to stop the discharge to the load. In this case, the reference voltage 12 is also held as data on software.

[0025]

As described above, according to the present invention, when a plurality of sealed alkaline batteries are used as an assembled battery, the terminal voltage of each of the sealed alkaline batteries is individually detected and hydrogen is detected. Since over discharge can be detected at a voltage higher than the gas generation voltage and discharge to the load can be stopped, there is an advantage that hydrogen gas can be prevented from being generated even if the charge and discharge characteristics of each battery vary. .

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a battery system for an automated guided vehicle according to the present invention.

FIG. 2 is a block diagram showing a configuration of a battery voltage monitoring unit 6 of the same embodiment.

FIG. 3 is a characteristic diagram showing discharge characteristics of an alkaline battery.

FIG. 4 is a characteristic diagram showing discharge characteristics for explaining a problem that occurs when a plurality of alkaline batteries are used as an assembled battery.

[Explanation of symbols]

 1-1 to 1-n battery 2 power receiving coupler 3 pressure sensor 5 internal pressure detection sensor 6 battery voltage monitoring unit (discharge stop control means) 10-1 to 10-n differential amplifier 11-1 to 11-n comparator 12 reference voltage 13 OR circuit 14 Relay driver SW1 contact Ry1 relay Ry1 'contact Ry2' contact L load

Claims (2)

[Claims] 1. A battery system for an automated guided vehicle, comprising a plurality of sealed alkaline batteries as an assembled battery, wherein terminal voltages of each of the sealed alkaline batteries are detected, and at least one terminal voltage is the sealed type. It is characterized by further comprising discharge stop control means for stopping the discharge of the plurality of sealed alkaline batteries to the load when the voltage becomes lower than a predetermined reference voltage set to a voltage higher than the hydrogen gas generation voltage in the alkaline battery. Battery system for automated guided vehicles. 2. The discharge stop control means is provided corresponding to the plurality of sealed alkaline batteries, and a plurality of differential amplifiers for detecting the terminal voltage of each of the sealed alkaline batteries; A plurality of comparison means provided corresponding to the sealed alkaline battery and comparing each of the terminal voltages output from the plurality of differential amplifiers with the reference voltage, and the output of the plurality of comparison means are ORed. The battery of the automatic guided vehicle according to claim 1, further comprising an OR circuit and a relay that opens a transmission path to a load of the plurality of sealed alkaline batteries based on a result of a logical operation of the OR circuit. system.