JP2894032B2 - Battery level detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery liquid level detecting device for detecting a decrease in battery level. In particular, it is an object of the present invention to easily detect liquid reduction in each battery when a plurality of batteries are connected in series to form a high voltage.

[0002]

2. Description of the Related Art As a conventional battery liquid level detecting device, there is a device described in Japanese Utility Model Publication No. Sho 53-211691, wherein a transformer or the like connected to an AC power supply is a constituent element, and the battery is reduced. Provides liquid detection and alarm devices. On the other hand, there is also a battery level detecting device that does not have the transformer. FIG. 8 is a diagram showing a battery liquid level detecting device which is a premise of the present invention. As shown in the figure, in the battery level detecting device having no transformer, while the battery level detecting sensor is immersed in the electrolyte in the battery cell, the potential of the cell is used as a signal (S _i ). When the electrolyte is insufficient and the electrolyte does not come into contact with the battery level sensor, the signal (S _i ) is opened. The input signal receives two states as input signals, and the switching transistor is operated by the input signals. By turning on an alarm lamp, an abnormality of a decrease in the battery liquid level has been detected. Here, a 12V or 24V battery is used as a battery of a general automobile. In addition, about the battery level detection device of FIG.
This will be described in detail in the section of Examples.

[0003]

However, in the conventional battery liquid level detecting device, when a power source is a battery such as a forklift or an electric vehicle, for example, a plurality of 12 V batteries are connected in series. The following problems occur. Since the battery liquid level detection sensor shows a different potential each time it is set to the electrolyte of a different battery, if the power supply voltage of the switching transistor is constant, the input voltage dividing resistor is set so that the input potential is constant. Must be changed each time. When the power supply voltage of the switching transistor is taken from the battery in which the battery level sensor is set, it is not necessary to change the input voltage dividing resistance as described above, but the potential of the output signal of the switching transistor is Since the liquid level detection sensor differs for each set battery and is too high to be used directly in the CPU, it is necessary to provide a voltage dividing resistor to the output of the switching transistor to make the output voltage constant. For this reason, a circuit constituting the battery level sensor becomes complicated. Accordingly, an object of the present invention is to provide a battery level detecting sensor having a simple circuit configuration even when a plurality of batteries are connected in view of the above problems.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention sets a sensor in the electrolyte of a battery and detects the potential of the electrolyte to prevent the battery level from dropping. A battery liquid level detection device to be detected is provided with a battery liquid level detection sensor, a photocoupler, a delay signal shaping unit, a comparator, a display, and a driving unit. The battery liquid level detecting sensor has a switching unit that is turned on / off by a signal from the sensor set in an electrolyte of any one of the plurality of batteries. The photocoupler is connected in series with the switching means and its photodiode is connected between the positive and negative electrodes of the battery. The delay signal forming unit delays a signal of a decrease in battery level from a phototransistor of the photocoupler for a predetermined time. The comparator compares the output signal of the delay signal forming unit with a reference signal to determine whether the battery level is low. The display displays the judgment of the battery level drop made by the comparator. The driving unit drives the display. Further, a battery level drop signal is input from each phototransistor of the photocoupler connected to the battery level detection sensor set to the electrolyte of any of the batteries connected to the plurality. And an OR circuit for outputting to the delay signal forming section. Also,
A relay switch may be provided between the electrode of the battery and the photocoupler. Further, the output signal of the photocoupler may be converted to a logic signal, and the logic signal may be used to delay the battery level drop signal for a predetermined time.

[0005]

According to the battery liquid level detecting device of the present invention, the battery liquid level detecting sensor is constituted even if the battery liquid level detecting sensor is set to the electrolytic solutions having different potentials of the electrolytic solution of the battery. Although the output of the sensor and the output of the switching transistor are electrically separated by a photocoupler, the configuration of the battery liquid level detection sensor and the photocoupler is common and simplified even if the potential of the electrolyte is different. This is useful when using a plurality of. Further, a plurality of battery liquid level detection sensors are attached to a plurality of batteries, respectively.
The circuit can simultaneously monitor these battery level sensors. In addition, the power consumption of the battery level sensor can be reduced by the relay switch.
Further, by making the output signal of the photocoupler a logical signal, processing by the CPU becomes possible, and monitoring of a large number of battery liquid level detection sensors becomes easy.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a battery liquid level detecting device according to a first embodiment of the present invention. FIG. 2 is a diagram illustrating a battery liquid level detection device according to a first embodiment. The configuration shown in the figure is an ignition switch 1 for an automobile or the like, and its positive electrode is connected to the ignition switch 1 and n
A battery 2 as a power source connected in series and having its negative electrode grounded, and one terminal 31 connected to the positive electrode (potential SV) of the m-th battery (B _m ) of the battery 2; Is a terminal 32 connected to the negative electrode (potential SG), one of them is a sensor 33 set to the electrolytic solution (potential Si), and one is a resistor 34 connected to the terminal 31 and the other of the sensor 33, respectively. 35, one of which is connected to the other of the terminals 32 and the other is connected to the other of the resistors 35, and whose base is connected to the other of the resistors 35 and 36 and whose emitter is connected to the sensor 3
A battery level sensor 3 comprising an npn-type switching transistor 37 connected to the other one of the resistors 3 and one of the resistors 36; and a DC / DC converter connected to the positive electrode of the battery 2 via the ignition switch 1. A voltage adjusting unit 4 for lowering the output voltage of the battery 2 to, for example, 12 V for stabilization; an anode of the voltage adjusting unit 4 being the other end of the resistor 34;
A photodiode 51 connected to the collector of the pn-type switching transistor 37, and a phototransistor 52 whose emitter is grounded and whose base receives light from the photodiode 51 at its base, one of which is electrically insulated from the other, A resistor 61 connected to the collector of the phototransistor 52, one of which is connected to the voltage adjusting unit 4
And a constant current source 62 connected to the other end of the resistor 61 and a capacitor 63 connected to the other end of the resistor 61 and the constant current source 62 and grounded on the other side. Delay signal shaping unit 6
And a comparator 7 having its non-inverting terminal connected to the other of the resistor 62 and the like and its inverting terminal connected to a reference voltage (V _REF ) to determine whether the sensor 33 is connected to the electrolytic solution. One is connected to the output of the voltage regulator 4 to display a warning about a decrease in the liquid level;
One of which is connected to the output of the comparator 7, one of which is connected to the other of the resistor 91 and the other of which is grounded, and one of which is connected to the output of the voltage regulator 4. Is connected to the resistor 93 and its base is connected to the resistor 9.
An npn transistor 94 having its collector connected to the other of the resistors 93, one of which is connected to the other end of the resistor 93, one of which is connected to the emitter of the npn transistor 94 and the other is grounded; A valve driver 9 is connected to the other end of the valve 8 and has a Darlington connection consisting of an npn transistor 96 whose base is connected to the emitter or the like of the npn transistor 94 and whose emitter is grounded. Here the diode D ₁ of the in the figure shows a protection during circuit reverse connection, the resistor 34 represents the resistance current limit flowing through the photodiode 51, the resistor 35 and 94 are transistors 37 and 94
The resistance 93 indicates the limiting resistance of the Darlington-connected collector separation portion. Battery 2
And the battery level sensor 3 are commonly grounded. R ₁ here resistor 34, 35 and 36 the resistance value of each, R ₁ = 5.1 as an example when the R ₂ and R ₃
KΩ, R ₂ = 15 KΩ and R ₃ = 7.5 KΩ.

Next, the operation of this embodiment will be described. When the liquid level of the electrolytic solution of the battery 2 in which the sensor 33 is set is normal, the potential Si of the output signal of the sensor 33 is higher than the potential SG of the negative electrode, so that a current flows to the base of the transistor 37 via the resistor 35. Flow, and at the same time, current can flow through the photodiode 51 of the photocoupler 5. At this time, the phototransistor 52 of the photocoupler 5
Is also turned on, the current I ₀ of the constant current source 62 of the signal shaping section 6 flows through the resistor 61, and the potential of the other end of the resistor 61 is V ₁ = I ₀ × R ₁₀ (R ₁₀ : the resistance of the resistor 61). resistance), and the V ₁ <V _{RE F.} Therefore, the output of the comparator 7 becomes “L (Low: ０0 V)”, and the transistors 94 and 96 are turned off. Therefore, the bulb 8 for displaying a warning is not turned on.

On the contrary, if the electrolyte level is insufficient, the sensor 3
Since the transistor 3 is open, the transistor 37 is turned off, and no signal is generated in the photocoupler 5, so that the phototransistor 52 is turned off. Then, the current I ₀ of the constant current source 62 is charged according to the following equation.

(Equation 1)Equation (1) and current I₀Due to a certain relation, other than the resistor 61
The potential at the end is V₁= I ₀× t / C. Where C is
And t is the phototransistor 5
It is time since 2 was turned off. And V₁≧ V
_REFTime t₁= V_REF× C / I₀With a delay of
The output of the comparator 7 becomes "H (High)" and the transistor
The base current flows through the heaters 94 and 96, and the bulb 8 lights up.
Perform warning display. Note that a certain delay time is given here
Means that the liquid level is tilted during running and the liquid level drops, and an alarm sign is displayed.
This is to prevent that. As described above, the configuration of FIG.
Unlike the configuration, the photocoupler 5 and the battery 2
Lie liquid level detection sensor 3 is detected because it is electrically separated
Regardless of the power system of the circuit, multiple series as well as parallel
Battery level at the connection point
You. In addition, the photocoupler 5 includes a plurality of batteries at arbitrary locations.
-2 B_mCan be freely combined as long as the pressure resistance allows
It is possible.

FIG. 2 is a diagram showing a battery level detecting sensor according to a second embodiment of the present invention. The second embodiment shown in FIG. 2 is an application of the first embodiment, and shows an example of a circuit for detecting the liquid level from three desired batteries among a plurality of batteries connected in series. That is, for example, the battery liquid level detection sensors 3A, 3B and 3C having the same configuration are connected to, for example, B ₁ , B ₂ and B ₃ of the battery _2, and the photocouplers 5A and 5B having the same configuration as the battery liquid level detection sensors 3A, 3B and 3C. And 5C are connected to each other, and pull-up resistors 61A, 61B are connected between the collectors of the phototransistors 52A, 52B, and 52C of the photocouplers 5A, 5B, and 5C and the output of the voltage adjusting unit 4.
And 61C are connected, and the phototransistors 52A, 52C
B and the collector of 52C are input and the output is
An OR circuit 64 (open collector output) connected to one of the terminals 1 is provided. Here, the resistors 61A, 61B and 61C and the OR circuit 64 constitute the signal shaping unit 6.

FIG. 3 is a diagram showing the OR circuit of FIG. This circuit includes the phototransistor 52 at their anodes.
A, 52B and 52C are connected to diodes 641A, 641B and 641C, one of which is connected to the cathode of each of the diodes 641A, 641B and 641C, and one of which is connected to the resistor 642. A resistor 643 whose other end is connected to the voltage power supply (-E _C ), an npn-type switching transistor 644 whose base is connected to the other end of the resistor 642 and whose emitter is grounded,
A resistor 645, one of which is connected to the collector of the switching transistor 644 and the other is connected to a voltage supply (E _C ), the base of which is connected between the collector of the switching transistor 644 and the resistor 645; A transistor 646 whose emitter is grounded and whose open collector output is output to the resistor 61
And

According to this embodiment, the basic principle is the same as that of FIG. 1, and the signals of the three battery level sensors 3A, 3B and 3C are transmitted to one valve 8 by the NOE circuit 64.
Can be displayed. Although the display shows the configuration by hardware, after the phototransistors 52A, B, C output of the photocouplers 5A, B, C in FIG. Effect can be obtained. Although the three battery liquid level detection sensors 3A, 3B and 3C have been described in the above example,
It is not limited to this number.

FIG. 4 is a diagram showing a third embodiment for reducing the current consumption of the battery liquid level detecting device. As shown in the figure, a relay switch 20 is provided on the line of the sensor 33 of the battery level sensor 3. This makes it possible to reduce current consumption when the battery level sensor 3 is OFF.

FIG. 5 is a view showing a battery level detecting device according to a fourth embodiment of the present invention. As shown in this figure,
A battery liquid level detection device using a liquid crystal display is shown,
That is, the battery 2 of the example B _4, and the battery level detecting sensor 3A and 3B to B ₅ are connected respectively, phototransistors 52A and 5 one of the resistors 61A and 61B are of the photocoupler 5A and 5B for the pull-up
2B are connected to the collectors of the phototransistors 52A and 52B, respectively, and the other is connected to a voltage power supply (5V). Control unit 1 connected to the other of 65A and 65B and configured by CPU
0 and the liquid crystal drive circuit 1 controlled by the control unit 10
1 and a display (liquid crystal) 12 driven by the liquid crystal drive circuit 11.

Next, the operation of this embodiment will be described. Battery
-2 B_FourAnd B_FiveIs normal, the sensor 33A in FIG.
And 33B detection potential Si_FourAnd Si_FiveTiger by signal
The transistors 37A and 37B are turned on, and the control unit 1
Signal V input to 0_FourAnd V _Five(Refer to the figure)_Fouras well as
V_Five= “0” level. Abnormality due to low liquid level
Sometimes, for example, the detection potential Si of the sensor 33A_FourIs OFF
State, the transistor 37A is also turned off,
Input potential V of control unit 10_FourIs connected to the pull-up resistor 61A.
5V or V_Four= “1” level. Below
Terry 2 B_FiveSimilarly, when the liquid level is low, V_Five=
It becomes “1”.

FIGS. 6 and 7 are flowcharts (parts 1 and 2) for providing a delay of 6 seconds in the control unit. Initialize the RAM (Randam Access Memmory), flag register, timer, etc. inside the CPU (step 10).
1). Sampling period T _S of the input signal V ₄ and V ₅ is determined whether becomes 0.1 seconds (step 102), T _S
= 0.1 seconds when it comes to reading the input state of V ₄ (step 103). If V ₄ = "1" is long if the liquid level is abnormal and abnormality flag FW4 for B ₄ of the battery 2 compared to that of previous FW4 = 0 and (clear) already (step 104), Count T _{i4 of} delay time counter
_Is started (step 105), and when the count T _i4 of the delay time counter _reaches 6 seconds (step 107), the abnormal flag FW4 = 1 is set (step 108). If V ₄ = “0” in step 103, the liquid level is normal. In this case, the count T _i4 of the delay time counter is set to 0 seconds (step 106), and the count T of the delay time counter is set in step 107. _{If i4} = 6 seconds has not been reached, the abnormality flag FW4 = 0 is set (step 109). If an abnormality has already been detected with the abnormality flag FW4 = 1 in step 104, the next step is performed. Proceed to.

[0016] Next, read the input state of V ₅ (step 110). If V ₅ = "1" liquid surface if is abnormal abnormality flag FW5 for B ₅ of the battery 2 compared to that of previous FW5 = 0 and (clear) already (step 111), The count T _i5 of the delay time counter is started (step 112), and the count T _i of the delay time counter is started.
_{When i5} = 6 seconds (step 114), the abnormality flag FW5 = 1 is set (step 115). Step 1
If V ₅ = “0” at 10, the liquid level is normal, and in this case, the count T _i5 of the delay time counter is set to 0 seconds (step 113). Further, at step 111, the count T _{i5 of the} delay time counter is set. If the time has not reached 6 seconds, the abnormality flag FW5 = 0 is set (step 116). If the abnormality has already been detected with the abnormality flag FW5 = 1 in step 111, the next step is performed. move on.

[0017] Then it is determined whether the abnormality flag FW4 = 1 (step 116), the abnormality flag FW4 = the display 12 of the battery 2 if 1 B ₄ may display an abnormal (step 118) , The abnormal flag FW4 = 0
Displays that is normal on the display unit 12 B ₄ of the battery 2 is equal to (step 119), the abnormality flag FW
5 = 1 or the determined (step 120), the abnormality flag FW5 = 1 a B ₅ of the battery 2 on the display 12 if the display is not operating normally (step 121), at the abnormality flag FW5 = 0 B ₅ of the battery 2 on the display 12 if any display that is normal (step 119).
Note that the count of the delay time counter is set to 6 seconds as an example, and the present invention is not limited to this.

[0018]

As described above, according to the present invention, the signal of each battery level sensor attached to a plurality of connected batteries is electrically connected to the subsequent circuit of the battery level sensor using a photocoupler. Separation made it easier to handle any battery and battery level sensor.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a battery liquid level detecting device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a battery liquid level detection sensor according to a second embodiment of the present invention.

FIG. 3 is a diagram illustrating a NOR circuit of FIG. 2;

FIG. 4 is a diagram showing a third embodiment for reducing the current consumption of the battery liquid level detecting device.

FIG. 5 is a diagram showing a battery liquid level detecting device according to a fourth embodiment of the present invention.

FIG. 6 is a flowchart (part 1) of giving a delay of 6 seconds in the control unit.

FIG. 7 is a flowchart (part 2) of giving a delay of 6 seconds in the control unit.

FIG. 8 is a diagram showing a battery liquid level detection device which is a premise of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ignition switch 2 ... Battery 3 ... Battery liquid level detection sensor 4 ... Voltage adjustment part 5 ... Photocoupler 6 ... Signal shaping part 7 ... Comparator 8 ... Valve 9 ... Drive part 10 ... Control part 11 ... Liquid crystal drive circuit 12 ... Display vessel

Claims (4)

(57) [Claims] 1. A battery liquid level detecting device for detecting a drop in the liquid level of a battery by setting a sensor for the electrolytic solution of the battery and detecting the potential of the electrolytic solution, A battery level detection sensor having a switching means for turning on and off with a signal from the sensor set in the electrolyte; and a series connection to the switching means and a photodiode connected between a positive electrode and a negative electrode of the battery. A delay signal forming unit that delays a signal of a decrease in battery level from a phototransistor of the photocoupler for a predetermined time; and compares an output signal of the delay signal formation unit with a reference signal to decrease the battery level. And a comparator for judging whether the battery liquid level has dropped. Liquid level detecting device. 2. A battery level drop signal from each phototransistor of the photocoupler connected to each of the battery level detection sensors respectively set in the electrolytes of any of the plurality of combined batteries. 2. The battery liquid level detecting device according to claim 1, further comprising an OR circuit for inputting a signal and outputting the signal to the delay signal forming unit. 3. The battery level detecting device according to claim 1, wherein a relay switch is provided between the electrode of the battery and the photocoupler. 4. The battery according to claim 1, wherein an output signal of the photocoupler is converted into a logic signal, and the signal for lowering the liquid level of the battery is delayed for a predetermined time by the logic signal. A battery level detecting device according to any one of the above.