JPS598790B2 - 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
By using a float, this "floating" and "sinking"
It was a specific gravity detection type that turned on and off contacts such as reed switches. 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 condensation monitor that has a simple configuration and can easily detect the battery capacity expressed as 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 operational amplifier that calculates the difference between the terminal voltage of the alternator and the terminal voltage of the alternator and outputs a difference signal; an integrating circuit that integrates the difference signal and outputs an integral signal; an arithmetic circuit that calculates the initial capacity of the battery based on the internal impedance of the battery when being supplied and outputs an initial capacity signal; A second operational amplifier that outputs a remaining capacity signal is provided.

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 initial capacity of the battery, is determined from the internal impedance during cranking, that is, when the starter current is flowing from the battery to the starter, and the amount of charged electricity is added to this initial capacity of the battery, and the amount of discharged electricity is subtracted. The remaining battery capacity can be detected. The above content will be further explained with reference to the figures.

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 s flowing through the starter 3 is determined by the battery terminal voltage being VB and the stunter terminal voltage being Vs. , where the value of resistor 2 (resistance of the starter cable) is Rs.

Also, if the open terminal voltage of the battery is E, then patch 1
The internal impedance ZB of the moon 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.

On the other hand, when charging and discharging the battery, that is, when the vehicle is running, a series circuit 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 flowing through the resistor 4 during discharging is represented by the charging current 12 flowing through the resistor 4 during charging, the amount of charge and discharge electricity can be expressed by the following equations. Therefore, the balance of income and expenditure can be detected as follows.

Further, the difference 12-11 between the charging current 2 and the discharging current from the closed circuit of the battery 1, the resistor 4, and the alternator 5 can be expressed by the following equation.

However, VA is the terminal voltage of alternator 5, R is resistance 4
is the resistance value of Therefore, from the above equations (6) and (7), the balance can be expressed by the following equation.

The balance amount above represents the difference between the amount of electricity charged and the amount of electricity discharged. If the amount of income and expenditure is positive, the amount of electricity charged is greater than the amount of electricity discharged, and when the amount of income and expenditure is negative, the amount of electricity discharged. This means that the amount of electricity is larger than the amount of electricity charged.

Therefore, the battery capacity can be detected by adding the income and expenditure amount of equation (8) to the battery initial capacity K of equation (3) above.

That is, when the balance amount is positive, the battery capacity increases, and when the balance amount is negative, the battery capacity decreases. Embodiments of the present invention will be described in detail below with reference to the drawings.

A starter 3 is connected to the battery 1 through a resistor 2, and an alternator 5 and an on-vehicle load 6 are connected through a resistor 4. A positive terminal of the battery 1 is connected to one input terminal of a first operational amplifier 7 via a relay contact 8 and a resistor 9. The output terminal of the operational amplifier 7 is connected to one input terminal of the operational amplifier 7 via a resistor, and is also grounded via a resistor 12 and a capacitor 9 that constitute an integrating circuit. A connection point between the resistor 12 and the capacitor 9 is grounded via a cancel switch 17, and is also connected to one input terminal of a second operational amplifier 13 via a resistor. The other input terminal of the operational amplifier 13 is
It is grounded via a resistor and connected to the output terminal of the operational amplifier 13 via a resistor. The output terminal of the operational amplifier 13 is connected to one input terminal of the comparator 15. The output end of the comparator 15 is grounded via a relay coil 16 that opens and closes the relay contact 8, and the other input end of the comparator 15 has a constant A2 input as a reference value. The output terminal of the alternator 5 is connected to the other input terminal of the operational amplifier 7 via a resistor 10 and is grounded via a resistor 11.

A liquid temperature sensor (not shown) that detects the terminal of the starter 3, the positive electrode of the battery 1, and the liquid temperature of the battery 1 is connected to the input terminal of the hold calculation circuit 14, and the terminal voltage of the battery VB and the terminal voltage of the starter are connected. Vs and battery liquid temperature T
A signal related to a is inputted, and a constant A1 determined depending on the battery type is also inputted.

The output end of the hold operation circuit 4 is connected to one input end of the operational amplifier 13 via a resistor. The operation of this embodiment will be explained below.

The operational amplifier 7 calculates the difference VA-VB between the alternator terminal voltage VA and the battery terminal voltage VB, and generates a difference signal e.
Outputs 1. That is, the voltage VB of the battery 1 is applied to one input terminal via each of the relay contact 8 and the resistor 9, and the terminal voltage V of the alternator 5 is applied to the other input terminal.
A is applied after being divided into predetermined voltages by resistors 10 and 11. Therefore, the operational amplifier 7 outputs a difference signal e1. Furthermore, since the difference signal e1 is applied to an integrating circuit composed of a resistor 12 and a capacitor 9, the current flowing through the capacitor 9 is i, and the voltage generated across it is E. Then, the following relationship holds true. (However, r is the resistance value of the resistor 12.) This equation (9) has a correlation with equation (8).

Therefore, the integrated voltage E. If you can find it, you have calculated the amount of income and expenditure. Integral voltage E, which is an integral signal. is operational amplifier 13
is input. On the other hand, the battery initial capacity K is calculated and held by the hold calculation circuit 14.

The calculation here is performed based on four conditions (VB, .V8, Ta.Al) so as to satisfy the relationship shown in equation (3). Calculation output of hold calculation circuit 14 (initial capacity signal)
That is, the initial battery capacity K is input to the operational amplifier 13 (the same terminal to which the integrated voltage is input). The operational amplifier 13 performs the calculation (K+EO).

This calculation result indicates the remaining capacity of battery 1 (if the amount of discharge is large, E indicates a negative value).Therefore, the alarm device or meter is driven based on this output battery remaining capacity signal. It becomes possible to monitor Sulepa Batsuteri 1. Here, countermeasures are required when the battery 1 becomes fully charged, and in the embodiment of the present invention, a comparator 15 and a relay 16 constitute a protection circuit. In other words, (K+EO) is one input of the comparator 15, A2 (a constant determined by the battery nominal capacity) is input to the other input terminal, and when (K+EO) exceeds A2, an output appears on the comparator 15. Do it like this. As a result, the relay 16 is driven and the relay contact 8 is turned off (
As a result, there will be no adverse effect on each amplification element, alarm device, meter, etc. Please note that if the ignition switch (not shown in the diagram) is turned off once, then turned on again. Sometimes (4) Due to the electric charge stored in the capacitor 9, the remaining battery capacity cannot be accurately indicated.

In order to prevent this problem, a cancel switch 17 is provided to short-circuit both ends of the capacitor 9 when the ignition switch is turned off. This makes it possible 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 fuse link between the battery and the alternator, the amount of electricity charged and discharged by the battery can be detected with even greater accuracy.

[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, 7,13...Operation amplifier, 9...Capacitor, 14...
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 with the starter during cranking to supply starter current to the starter, the difference between the terminal voltage of the battery and the terminal voltage of the alternator is detected. a first operational amplifier that calculates and outputs a difference signal; an integrating circuit that integrates the difference signal and outputs an integral signal; and an internal impedance of the battery when a starter current is supplied from the battery to the starter. a second operational amplifier that adds the integral signal and the initial capacity signal to determine the battery remaining capacity and outputs the battery remaining capacity signal; A battery condensation monitor characterized by being provided with.