JPH0333121Y2 - - Google Patents

Description

[Detailed explanation of the idea] Industrial applications This invention relates to a storage battery monitoring device.

Prior Art and its Problems The most common and accurate method for monitoring the capacity of a storage battery is to measure the electrolyte specific gravity and estimate the capacity from that value. An application of this is to immerse a specific gravity sensor, such as a float, in an electrolytic solution, convert the displacement into an electrical signal, amplify it, and display it as a capacitance. However, with this method, it is complicated to convert the displacement of the float etc. into an electrical signal, and as the temperature rises, dissolved oxygen in the electrolyte becomes bubbles and adheres to the float surface, which tends to cause errors and requires temperature correction. Problems include that they are unsuitable for mobile storage batteries that are subject to vibrations.

Another method for monitoring the capacity of a storage battery is to interpret changes in the specific gravity of the electrolyte as changes in the refractive index of light. However, this method also has problems, such as the fact that the prism becomes dirty and errors tend to occur, that an amplifying device is required, and that the device itself becomes complicated. For these reasons, devices that monitor storage battery capacity from electrolyte specific gravity are only used in some cases.

An alternative to these methods is a voltage detection type capacitance detection device. This estimates the capacity based on the change in battery voltage, and does not require a sensor such as a float. However, since this method uses the voltage when the storage battery is operating as the standard, if the load differs significantly, the degree of voltage drop will also differ, and the reference value must be reset depending on the type of load. is necessary. This is particularly a problem when the load fluctuates significantly depending on the operating conditions, such as in a forklift vehicle.

Purpose and Structure of the Invention It is an object of the present invention to provide a storage battery monitoring device that eliminates the above-mentioned conventional drawbacks.

That is, the present invention has a voltage detection mechanism 15, a voltage storage mechanism 16, a display mechanism 17, and a reset/correction mechanism 18, wherein the voltage detection mechanism 15 detects the open circuit voltage of the storage battery, and the voltage storage mechanism 16 is for storing the open circuit voltage of the storage battery detected by the voltage detection mechanism 15, and the display mechanism 17 displays the open circuit voltage of the storage battery stored by the voltage storage mechanism 16 using a meter or a plurality of LEDs.
Each time a new open-circuit voltage of the storage battery occurs, the reset/correction mechanism 18 lowers the open-circuit voltage of the storage battery previously stored in the voltage storage mechanism 16, and then displays the new open-circuit voltage of the storage battery. This relates to a storage battery monitoring device that stores open circuit voltage.

The storage battery monitoring device according to the present invention is suitable for detecting the capacity of a storage battery that is used intermittently, such as a forklift truck, rather than one that is used continuously, such as a storage battery for an automobile, and is suitable for detecting the capacity of a storage battery that is used intermittently, such as a forklift vehicle. Rather than detecting the open circuit voltage, it attempts to achieve its purpose by detecting the open circuit voltage. This applies the fact that the open circuit voltage of a storage battery has a correlation with its capacity. Therefore, there is no need to reset the reference value depending on the type of load, and the capacity can be accurately displayed even when the device is left unused.

In the case of forklift vehicles, the purpose of use
Generally, storage batteries are not used continuously for long periods of time with a constant load, but are used intermittently at short intervals, or the usage load changes frequently. This also applies to electric vehicle storage batteries and electric vehicle storage batteries. The stable value of the open circuit voltage of a lead-acid battery is correlated with the capacity of the storage battery or the electrolyte specific gravity value. Therefore, the open circuit voltage of a storage battery that is used intermittently decreases with a constant slope as the capacity decreases, and the capacity can be detected from this open circuit voltage value. FIG. 2 shows the voltage progression state during this intermittent use. The present invention detects this open circuit voltage, stores it, and displays it as a capacitance. Here, a capacitor is used as the voltage storage mechanism. Generally, capacitors store the open circuit voltage before discharge unless they are forced to discharge. Even if the capacitor is discharged by a circuit, a time constant that matches the capacitance drop cannot be obtained, and it changes every time there is a large voltage fluctuation such as discharging or leaving the capacitor, and it is difficult to obtain a capacitance display characteristic that shows a linear capacitance drop. Can not. In the storage battery monitoring device according to the present invention,
A reset/correction mechanism that discharges the capacitor every time a new open circuit voltage of the storage battery occurs to lower the storage battery open circuit voltage stored in the capacitor, and then stores the new open circuit voltage in the capacitor.
No matter how the storage battery voltage fluctuates, the capacity can always be displayed smoothly.

Embodiment FIG. 1 is a circuit diagram of an embodiment of a storage battery monitoring device according to the present invention. In the figure, 15 is a voltage detection mechanism, 16 is a voltage storage mechanism, 17 is a display mechanism, and 18 is a reset/correction mechanism. 1 is a storage battery to be monitored, and 2 is a load. Voltage detection mechanism 15
is composed of resistors 3 and 4, and divides the open circuit voltage of the monitored storage battery 1 into predetermined values. The voltage storage mechanism 16 is composed of a capacitor 7 and stores the open circuit voltage of the storage battery detected by the voltage detection mechanism 15. The display mechanism 17 is a linear IC5 for LED lighting.
and a plurality of LEDs 14, and displays the open circuit voltage of the storage battery stored in the voltage storage mechanism 16 as a capacity. Reset/correction mechanism 1
8 consists of resistors 8 and 11, a transistor 9, and a capacitor 10, and each time a new open-circuit voltage of the storage battery is generated, the open-circuit voltage of the storage battery that has been stored in the voltage storage mechanism 16 is lowered, and then the open-circuit voltage of the storage battery is reduced. This is to store a new open circuit voltage. 6 is a backflow prevention element, and a resistor 3 that constitutes the voltage detection mechanism 16
and 4, and an input terminal of an LED lighting linear IC 5, which is a part of the display mechanism 17. The negative electrode of the backflow prevention element 6 is an LED
This is the lighting linear IC side. The capacitor 7 that constitutes the voltage storage mechanism 16 is a linear IC for LED lighting.
are connected in parallel to the inputs of the Of the components of the reset/correction mechanism 18, the resistor 8 and the transistor 9
The emitter and collector are connected in series, and both are connected in parallel with the capacitor 7 of the storage mechanism 16. The capacitor 10 and the resistor 11 that constitute the reset/correction mechanism 18 are connected in series, and both
It is connected in parallel with a resistor 4 which is a component of the voltage detection mechanism 15. Also, capacitor 10 and resistor 1
The connection point 1 is connected to the base of transistor 9. 12 and 13 are constant voltage diodes.

FIG. 2 is a voltage transition state diagram during intermittent use of a storage battery for a forklift vehicle or an electric vehicle.
As mentioned above, fork lift vehicles are mainly used for on-site work, and are generally not operated continuously for long periods of time, but are operated intermittently every hour. Also, in the case of electric vehicles, due to their characteristics, they are not used for long-distance continuous operation, but are generally used for short-term intermittent operation, such as when collecting and delivering luggage. Under these conditions,
Intermittent operation is repeated at 5-10 minute intervals.
Therefore, the voltage characteristics of the storage battery in these cases are expressed as shown in FIG. As is clear from this figure, the voltage at the time of discharge cessation, that is, the stable value of the open circuit voltage, decreases linearly with the depth of discharge. The storage battery monitoring device according to the present invention is
This method utilizes this open circuit voltage-capacitance characteristic.
In the case of this embodiment, the open circuit voltage of the monitored storage battery 1 is divided by the resistors 3 and 4 that constitute the voltage detection mechanism 18, and the capacitor 7 that constitutes the voltage storage mechanism 16 is charged with the voltage across the resistor 4. From the division ratio between the capacitor voltage and the open circuit voltage, it is regarded as the open circuit voltage of the storage battery. The capacitor used is a resistive leakage capacitor, which is less susceptible to leakage current within the capacitor and ambient temperature. This allows the voltage once stored to be held for a long time. The input impedance of the LED lighting linear IC 5 is very high, and the capacitor is not discharged from the input side of the LED lighting linear IC.
Furthermore, since the resistor 11 has no voltage, the parallel-connected transistor 9 is in an OFF state, so that the capacitor is not discharged through the external circuit. Therefore, the once memorized open circuit voltage (point A in Figure 2)
is held as it is, and its state is displayed as a capacitance on the LED 14. When the use of the monitored storage battery 1 is interrupted, the voltage rapidly increases (point C in FIG. 2).
The capacitor storage voltage remains constant as shown by dashed lines AC in FIG. As the open circuit voltage of the monitored storage battery 1 increases, the voltage detection mechanism 15 detects this. Along with this, the reset
A charging current flows through the capacitor 10 in the correction mechanism 18. An induced voltage is generated across the resistor 11, and the transistor 9 is instantaneously turned on. As a result, the capacitor 7 forming the voltage storage mechanism 7 is discharged through the resistor 8 in the reset/correction mechanism 18, so that the capacitor voltage decreases. This continues until the capacitor voltage and the open-circuit voltage of the monitored storage battery 1 become equal (Fig. 2D). When the open-circuit voltage of the monitored storage battery 1 reaches point D in Fig. 2, the reset occurs.
Since the induced voltage of the resistor 11 of the correction mechanism 18 is lower than the conduction voltage of the transistor 9, the transistor
It turns OFF and the capacitor discharge stops. This is shown by the broken line C→D in FIG. As the open circuit voltage increases further, the capacitor begins to charge again and stores the value of the stable point B of the open circuit voltage. By repeating this process, each time a new open-circuit voltage occurs in the monitored storage battery, the previously stored voltage is temporarily lowered, and then the new voltage is stored. In the present invention, the process of once lowering the capacitor voltage of the voltage storage mechanism 16 (from C to D in FIG. 2)
This is called a reset, and the process of matching the reset capacitor to the open circuit voltage of the monitored storage battery is called a correction, and a mechanism that has both of these functions is called a reset/correction mechanism.

The voltage stored in the capacitor 7 of the voltage storage mechanism 16 is impedance-exchanged by the LED lighting linear IC 5, and the number of LEDs 1 proportional to the voltage is
By lighting up 4, the capacity of the monitored storage battery is displayed.

The capacity of the storage battery changes according to a hypothetical capacity drop characteristic X (see FIG. 2) drawn by the stable value of the open circuit voltage.
Therefore, the smaller the dissociation between the virtual capacity drop characteristic X and the point C or the point D, the more accurate and smooth the capacity display can be. In actual use of fork cars, electric vehicles, etc., continuous use is frequently performed, so it is possible to always know the capacity close to the direct value, and to obtain a capacity drop characteristic that is so smooth that it cannot be seen on the display. can. Therefore, according to the storage battery monitoring device according to the present invention, sudden changes in the display section, which are seen in conventional voltage type capacity meters, are eliminated, and a more accurate capacity can be determined. Furthermore, there is no need to change the reference value depending on the type of load, and the capacity can be displayed even when the storage battery is left unused.

The implementation of the storage battery capacity monitoring device according to the present invention is not limited to this embodiment. For example, instead of a linear IC for LED lighting, an operational amplifier,
A meter can also be used instead of an LED.

Effects of the invention According to the storage battery monitoring device according to the invention, it is possible to know more accurate capacity of storage batteries that are used intermittently, and there is no need to reset the reference value depending on the type of load. Since the capacity can be detected even when the vehicle is left unused, it is ideal for forklift vehicles, electric vehicles, etc., and its industrial value is great.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of the storage battery monitoring device according to the present invention, and Fig. 2 shows an example of voltage transition characteristics during cycle discharge of a load that requires discharging suspension, such as a storage battery for a forklift vehicle or an electric vehicle. It is a diagram. 1...Monitored storage battery, 2...Load, 3, 4...
Resistor, 5... Linear IC for LED lighting, 6... Backflow prevention element, 7... Capacitor, 8, 11... Resistor, 9... Transistor, 10... Capacitor,
14...LED, 15...voltage detection mechanism, 16...
... Voltage storage mechanism, 17... Display mechanism, 18... Reset/correction mechanism.

Claims (1)

[Claims for Utility Model Registration] It has a voltage detection mechanism 15, a voltage storage mechanism 16, a display mechanism 17, and a reset/correction mechanism 18, the voltage detection mechanism 15 detects the open circuit voltage of the storage battery, and the voltage storage The mechanism 16 is for storing the open circuit voltage of the storage battery detected by the voltage detection mechanism 15, and the display mechanism 17 is for displaying the open circuit voltage of the storage battery stored by the voltage storage mechanism 16 on a meter or a plurality of LEDs.
Each time a new open-circuit voltage of the storage battery occurs, the reset/correction mechanism 18 lowers the open-circuit voltage of the storage battery previously stored in the voltage storage mechanism 16, and then displays the new open-circuit voltage of the storage battery. A storage battery monitoring device that memorizes open circuit voltage.