JPS598789B2 - Battery condensation monitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a battery condensation monitor that monitors the battery capacity of an automobile battery.

In a car, if the capacity of a battery can be confirmed while the car is running, the driver can take prompt action depending on the condition.

For example, if the driver becomes aware of a decrease in battery capacity while driving, he or she can cut off the electrical load in advance to the extent that it does not cause any problems (configure a backup system that does this manually or automatically). This makes it possible to prevent melting of the catalytic converter due to a dead battery or ignition failure. The battery condensation monitor that was traditionally considered for this purpose was
It was a specific gravity detection type that used a float to turn on and off the contacts of a reed switch, etc. by floating this degree by one angle. However, this type of monitor has the following drawbacks. (a) During rapid charging and discharging, there is not necessarily a fixed relationship between the specific gravity and capacity of the battery.

(b) Errors occur due to fluid replacement. (c) Difficult to detect as an analog signal.

(d) Malfunctions occur due to vehicle vibrations. These drawbacks pose a major obstacle to practical application.

Therefore, there has been a strong desire for a battery conditioning monitor that does not have these drawbacks. The present invention has been made in view of the above-mentioned conventional drawbacks, and an object of the present invention is to provide a battery condition monitor that has a simple configuration and can easily detect the battery capacity expressed by the total amount of electricity. .

In order to achieve the above object, the present invention has a battery condensation monitor that detects the remaining capacity of a battery that is connected in parallel with an alternator and is connected in parallel with a starter during cranking to supply starter current to the starter. a first integrating circuit that integrates the discharge current flowing out from the alternator to determine the amount of discharged electricity; a second integrating circuit that integrates the charging current flowing from the alternator to the battery and determines the amount of charged electricity; and the photovoltaic electricity amount. a first operational amplifier that subtracts the discharged amount of electricity from the battery to obtain a difference amount of electricity; and an arithmetic circuit that calculates the initial capacity of the battery based on the internal impedance of the battery when the starter/starter current is supplied from the battery. and a second operational amplifier that adds the difference electrical quantity to the battery initial capacity to determine the remaining battery capacity.

Here, the principle of the present invention will be explained.

It is known that there is a certain relationship between the battery's internal impedance, that is, the output impedance during discharge, and the battery capacity.Especially when discharging a large current such as a starter current, the internal impedance and battery capacity are approximately proportional. , the battery capacity can be determined from the internal impedance.

Therefore, the battery capacity, that is, the battery initial capacity, is determined from the internal impedance during cranking, that is, when the starter current is flowing from the battery to the starter, and the difference electricity quantity obtained by subtracting the discharge electricity quantity from the charging electricity quantity is calculated from this battery initial capacity. By adding them, the remaining battery capacity can be detected. The above content will be further explained with reference to the drawings.

During cranking, a series circuit consisting of a resistor 2 (resistance of the starter cable) and the starter 3 is connected in parallel to the battery 1, so the starter current 1s flowing through the starter 3 is the battery terminal voltage VBl, the starter terminal voltage Vs, and the resistance 2 (resistance of the starter cable) is expressed as Rs.

Further, assuming that the open terminal voltage of the battery is E, the internal impedance ZB of the battery 1 is expressed by the equation (1) above.

The above open terminal voltage E does not change much due to the battery capacity, and the value Rs of the resistor 2 is constant. Therefore, if these values are ignored and the battery capacity is corrected by the battery liquid temperature Ta, the battery initial capacity K is It can be expressed by the following equation.

However, A1 is a constant determined by the battery type.

When the battery is charged and discharged, that is, when the vehicle is running, a series circuit consisting of a resistor 4 (wire resistance between the battery and the alternator) and the alternator 5 is connected in parallel to the battery 1, and an on-vehicle resistor 6 is connected in parallel to the alternator 5. The battery is charged and discharged.

Therefore, if the discharging current that flows through the resistor 4 during discharging is taken as , and the charging current that flows through the resistor 4 during charging is taken as 2, the amount of charge and discharge electricity can be expressed by the following equations. Therefore, the differential electrical quantity can be detected as follows.

The above-mentioned difference electricity quantity represents the difference between the charging electricity quantity and the discharging electricity quantity. When the difference electricity quantity is positive, the charging electricity quantity is larger than the discharging electricity quantity, and when the difference electricity quantity is negative, the charging electricity quantity is larger than the discharging electricity quantity. This indicates that the amount of electricity discharged is greater than the amount of electricity charged. Therefore,
The remaining battery capacity can be detected by adding the difference electricity amount in equation (6) to the battery initial capacity K in equation (3) above.

That is, when the difference in the amount of electricity is positive, the battery capacity increases, and when the difference in the amount of electricity is negative, the battery capacity decreases, so that the remaining battery capacity can be detected. Embodiments of the present invention will be described in detail below with reference to the drawings. A series circuit of a resistor 2 and a starter 3 is connected in parallel to the battery 1, a series circuit of a resistor 4 and an alternator 5 is connected in parallel, and an on-vehicle load 6 is connected in parallel to the alternator 5. The positive terminal of the battery 1 is connected to the first operational amplifier 7 via a diode 8 whose anode is connected to the positive terminal of the battery, a resistor 9, a relay contact 10, and a resistor 11.
The operational amplifier 7 is also connected to one input terminal of the operational amplifier 7 via a diode 14 whose cathode is connected to the positive terminal of the battery, a resistor 15, and a resistor 16.

The connection point between the relay contact 10 and the resistor 11 is connected to the output end of the alternator 5 via the capacitor 18, and the connection point between the resistor 15 and the resistor 16 is connected to the output end of the alternator 5 via the capacitor 17. ing. The resistor 9 and capacitor 18 described above constitute a first integrating circuit, and the resistor 15 and capacitor 17 constitute a second integrating circuit.
Further, the output terminal of the alternator 5 is connected to the other input terminal of the operational amplifier 7 via a resistor 12, and the negative pole of the battery is connected via a resistor 13. The output terminal of the operational amplifier 7 is connected to the operational amplifier 7 via a resistor.
is connected to one input terminal of the
is connected to one input terminal of an operational amplifier 19. One input terminal of this operational amplifier 19 is grounded via a resistor. Each input terminal of the hold arithmetic circuit 20 receives signals related to a terminal voltage VB of the starter, a terminal voltage Vs of the starter, a battery liquid temperature Ta, and a constant A1 determined by the battery type. The circuit 20 calculates the battery initial capacity K based on the above equation (3).
is calculated and held, and the battery initial capacity K is output to one input terminal of the operational amplifier 19 via a resistor. The other power end of the operational amplifier 19 is grounded through a resistor and connected to the output end of the operational amplifier 19 through the resistor.

The output terminal of the operational amplifier 19 is connected to one input terminal of the comparator 21. The output end of the comparator 21 is grounded via a relay coil 22 that opens and closes the relay contact 10, and the other input end of the comparator 15 has a constant A2 input as a reference value. The operation of this embodiment will be explained below.

The terminal voltage VB of the battery 1 is applied to one input terminal of the operational amplifier 7 through each of a diode 8, a resistor 9, a relay contact 10, and a resistor 11, and the terminal voltage VA of the alternator 5 is applied to the other input terminal. It is configured such that a voltage divided by resistors 12 and 13 is applied.

Furthermore, a diode 14 and resistors 15 and 16 are connected between the battery 1 and one input terminal of the operational amplifier 7.
There is a capacitor 1 between the connection point of 5 and 16 and the alternator 5.
7 is inserted, when the terminal voltage VA of the alternator 5 becomes higher than the terminal voltage VB of the battery 1 (which means that the vehicle is running under a light load), the alternator 5 and the capacitor 17, resistance 15,
Current 12 flows through each of the diodes 14, charging the capacitor 17. On the other hand, relay contact 10, resistance 1
Since a capacitor 18 is inserted between the connection point of battery 1 and alternator 5, when terminal voltage VB of battery 1 is higher than terminal voltage VA of alternator 5, diode 8
A current 11 flows through each of the resistor 9, the relay contact 10, and the capacitor 18, and the capacitor 18 is charged. Here, when the voltage between both terminals of the capacitor 18 is set as e1, and the voltage between both terminals of the capacitor 17 is set as E2, the following relational expression holds true.

of There is a relationship between

Therefore, the output voltage (differential quantity of electricity) EO of the operational amplifier 7 is {
-(e1-E2)}. This means that {−(Fld
t (discharged electricity amount) 12dt (charged electricity amount)}, and when the discharged electricity amount is larger than the charged electricity amount, the output voltage is E. will increase in the negative direction, and vice versa, it will increase in the positive direction. This output voltage E.

is applied to the operational amplifier 19 after being divided into predetermined voltages,
The operational amplifier 19'' has a battery initial capacity K and an output voltage E.
In other words, the remaining battery capacity (K+
EO? Output. In this case, the battery capacity K is obtained by calculating and holding a value that satisfies the above-mentioned equation (3) using the hold calculation circuit 20 and then applying it to the operational amplifier 19. (K
+EO) always represents the remaining capacity of battery 1.
Therefore, the battery 1 can be monitored by driving an alarm device or a meter based on this output. Here, countermeasures are required when the battery 1 becomes fully charged, but in the embodiment of the present invention, the comparator 21 and the relay 2
2 constitutes a protection circuit.

In other words, (K + EO) is input to one side of the comparator 21, A2 (a constant determined by the battery nominal capacity) is input to the other input terminal, and when (K + EO) exceeds A2, the output is displayed in the comparator 21. make sure that you are As a result, the relay coil 22 is excited and the relay contact 10 is turned off, so that each amplification element, alarm device, meter, etc. are not adversely affected. Note that when the ignition switch (not shown) is once turned off and then turned on again, the remaining battery capacity will no longer be accurately indicated due to the charges stored in the capacitors 17 and 18. To prevent this problem, cancel switch 2
3 is provided so that both ends of the capacitors 17 and 18 can be short-circuited in conjunction with each other when the ignition switch is turned off. This allows you to operate the monitor from the very beginning and take accurate measurements each time. As is clear from the above, according to the present invention, it is possible to obtain the effect that the battery remaining capacity can be detected purely electronically with a simple configuration.

Note that by inserting a shunt resistor or a fusible link between the battery and the alternator, the amount of electricity charged and discharged from the battery can be detected with even greater accuracy. This can be easily understood from the fact that the value R of the resistor 4 is inversely proportional to the discharging current or charging current.

[Brief explanation of the drawing]

The figure is a circuit diagram showing an embodiment of the present invention. 1...Battery, 2,4...Resistance, 5
...Alternator, 7,19...Operation amplifier, 17,18...Capacitor, 20...
...Hold calculation circuit.

Claims (1)

[Claims] 1 In a battery condensation monitor that detects the remaining capacity of a battery that is connected in parallel with the alternator and the starter during cranking to supply starter current to the starter, the amount of discharged electricity is calculated by integrating the discharge current flowing out of the battery. a first integrator circuit that calculates
a second integrating circuit that integrates the charging current flowing into the battery from the alternator to determine the amount of charged electricity; and a first integrating circuit that calculates the difference amount of electricity by subtracting the amount of discharged electricity from the amount of charged electricity.
an operational amplifier, an arithmetic circuit that calculates the initial battery capacity based on the internal impedance of the battery when starter current is supplied from the battery to the starter, and a calculation circuit that calculates the battery remaining capacity by adding the difference electricity quantity to the battery initial capacity. A battery condensation monitor characterized by comprising a second operational amplifier for determining capacity.